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Thread: Certified Pool Operator (CPO) training -- What is not taught

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    Certified Pool Operator (CPO) training -- What is not taught

    This thread will discuss some of the topics that are either not taught or are taught with incorrect or incomplete information, at least as far as I can tell from those who have had CPO training. If any of you have had recent CPO training and can comment on whether the following is accurate in terms of not currently being taught, then that would be helpful and I will update this post accordingly. The purpose is to readily be able to list what areas need to be improved in the event that NSPF becomes willing to improve the CPO course or as a guide for those of you who take such courses to give constructive feedback. This thread may also be referenced from other threads where someone is quoting CPO information that is incomplete or inaccurate.

    CPO certification is great, but none of the NSPF CPO, APSP or IPSSA courses/manuals teach the following information, at least not completely. Some of these courses are more targeted to commercial/public pool operation and cover many things other than just water chemistry that I have focused on below. I purchased the 2009 "CPO Handbook, National Swimming Pool Foundation" with front cover title "Pool & Spa Operator™ Handbook" and it is a very impressive manual. It is well organized, in full color, with many charts and examples and a lot of very good information. Nevertheless, it could be improved by covering the following information. In the following, the term "the handbook" refers to the handbook with the officially referenced name I just gave in quotes.

    [EDIT] A detailed report of suggestions for improvement to the Handbook is in this Word file (or this PDF document) that I wrote. [END-EDIT]

    Effects From Different Sources of Chlorine
    The following are chemical facts independent of concentration of product or of pool or spa size [EDIT] (added info on affect on TA after accounting for chlorine addition and usage/consumption): [END-EDIT]

    For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6.1 ppm and decreases Total Alkalinity (TA) by 7.1 ppm.
    For every 10 ppm FC added by Dichlor, it also increases CYA by 9.1 ppm and decreases TA by 3.5 ppm.
    For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm and increases TA by about 0.4 ppm.
    For every 10 ppm FC added by ANY source of chlorine, there will be 8.2 ppm salt from when the chlorine gets used/consumed and converts to chloride. For bleach, chlorinating liquid, and lithium hypochlorite, there is an additional 8.2 ppm salt added upon addition so the net result is 16.5 ppm salt from these sources and the TA rises by 0.1-0.6 ppm depending on the amount of "excess lye" in the product.

    The handbook does not disclose the above information for any of the chlorine sources except for Dichlor where it is stated that one pound per 10,000 gallons provides (for dihydrate) 6.7 ppm FC and 6 ppm stabilizer.

    Using the chemical facts from different chlorine sources noted above, even at a low 1 ppm FC per day chlorine usage, this means an increase in CYA from Trichlor of nearly 110 ppm after a 6 month swim season if there is no dilution of the water. The salt added by bleach, chlorinating liquid or lithium hypochlorite, even at 2 ppm FC per day is about 590 ppm after 6 months. If there is continual dilution of the water annually of around 1/3rd the pool water volume (equivalent to a one-time dilution of around 28%), then the long-term CYA level in the example I gave would be around 330 ppm while the long-term salt level in the other example would be 1770 ppm. Remember that SWG pools usually have 3000 ppm salt. So it takes much more dilution to keep CYA in check than to keep salt levels in check (and in my examples I used double the chlorine usage rate for the salt example than for the CYA example, just to emphasize the point). A similar analysis using Cal-Hypo with a low 1 ppm FC per day would result in a long-term CH level of 383 ppm, but higher chlorine usage would result in higher CH levels so use of Cal-Hypo is more manageable than stabilized chlorine (assuming 1/3 pool volume annual dilution rates done via continuous dilution).

    The handbook talks about the side effects, but without being specific (as above) so people don't have a clear idea of how quickly CYA or CH or salt build up and why that's a bigger problem for CYA than for CH which is a bigger problem than for salt (more on that later).

    Total Dissolved Solids (TDS)
    The industry says that high TDS is a problem. This is not exactly true. TDS is mostly salt and is only an issue if it gets very high (remember that SWG pools typically use 3000 ppm salt) in terms of increased corrosion rates from the higher conductivity (and chloride levels for stainless steel). TDS can be a rough measure of the age of the water (depending on bather load and source of chlorine used) but the main problem with higher TDS in residential pools is that it usually is associated with higher CYA levels from continued use of stabilized chlorine (Trichlor or Dichlor) and it is the higher CYA level that is the true source of some problems; in particular, algae growth.

    In commercial/public pools where most of the chlorine demand is from bather load, the higher TDS from accumulated chloride that came from chlorine can be a proxy indicator for a buildup of unoxidized chemicals from bather waste and other organic material, but using regular water replacement as a function of bather load is a more reliable way of keeping the water fresh. One can also measure the overnight chlorine demand to determine if there are substances in the pool increasing chlorine demand. This analysis should be done after eliminating the known issues from a low FC/CYA ratio or other water chemistry parameters.

    The handbook does refer to TDS as a proxy for organic matter buildup and increases the probability of metal corrosion, but doesn't note that in low bather load pools, such as most residential pools, TDS is mostly salt and the organic buildup may be relatively low.

    Chlorine/CYA Relationship
    The courses (and handbook) do not teach about the true effects of CYA on chlorine, even though this has been known since at least 1974 definitively determined in this paper. This is the technical foundation for the chlorine/CYA chart though this chart was originally developed more from observational experience by Ben Powell (more on that later below) based on the minimum FC/CYA levels for preventing algae growth. At a pH near 7.5, the equivalent Free Chlorine (FC) level with no CYA in terms of the same active chlorine (hypochlorous acid) concentration is roughly close to the FC/CYA ratio as derived in this post. So pools with an FC that is roughly 10% of the CYA level are equivalent to pools with an FC of around 0.1 ppm and no CYA. This is at cooler temperatures (closer to 77F so OK with pools in the 80-85 range; spas at 100-104F have a higher effective FC with no CYA).

    The FC test does not measure active chlorine (hypochlorous acid) alone, but also measures hypochlorite ion and, most importantly measures all of the chlorine bound to CYA (i.e. chlorinated isocyanurates) since this gets released quickly in the time of the test (see this paper). Looking at FC alone without consideration of CYA gives a false sense of security since it does not measure the chlorine level responsible for most of the sanitation and oxidation. The reaction rates for chemical reactions are based on the instantaneous concentration, not on whether a chemical gets replenished by conversion from another form (i.e. chlorine bound to CYA). One should stop thinking of FC as meaning anything in terms of chlorine strength when there is CYA in the water. FC is simply a measurement of the total reservoir of chlorine available and NOT a measure of its active strength. The FC/CYA ratio (or scaled up version for spas) is the relevant number for chlorine's true strength for sanitation and oxidation.

    I and others who are technically oriented on this forum have pored through the scientific literature and found that the chlorine/CYA relationship holds extremely well in almost every case, be it for killing of bacteria (here, here, here, here, here), inactivation of viruses (here, here), protozoan oocysts (here, here, here, here), inhibition of algae growth (this paper claimed no correlation, but real pools say otherwise; Sommerfeld never wrote back to me when I questioned this), and oxidation of ammonia and organics (here) as well as correlation with ORP (see this post, this paper and this paper). I've also gone through field study data where the industry makes claims that only Free Chlorine (FC) matters in "real pools" yet I saw that bacteria are killed so easily that you can't even draw that conclusion from such studies and that hypochlorous acid (HOCl) is at least as good a predictor though they never looked at that correlation nor the FC/CYA ratio as a proxy (see this thread).

    The handbook does not talk about the chlorine/CYA relationship in detail and only indicates that with CYA in the water, higher chlorine concentrations or contact times are needed to inactivate cryptosporidium and that excessive levels of CYA may lead to an increased risk of algae.

    TA and its Effect on Rising pH
    The courses do not clearly explain how Total Alkalinity (TA), and specifically the carbonate portion of TA, is a SOURCE of rising pH so that as counter-intuitive as it may seem, a lower TA results in a lower rate of pH rise over time in most cases (when the pH rise is due to carbon dioxide outgassing). They do not teach that pools are intentionally OVER-CARBONATED to provide a pH buffer and to protect plaster and that this over-carbonation is the primary source of pH rise in pools using hypochlorite sources of chlorine. They do say to use a lower TA range of 80-100 ppm vs. 100-120 for acidic sources of chlorine such as Trichlor, but even lower TA levels may be needed in some cases (especially in spas using the Dichlor-then-bleach method). The ratio of how far out-of-equilibrium the carbon dioxide is in the water vs. the air at various pH and TA levels is shown in this chart though the rate of carbon dioxide outgassing appears to be related to the square of the TA rather than being linearly related (that is, the outgassing rate greatly outpaces the additional pH buffering at higher TA levels).

    The handbook indicates that at higher levels of TA, the pH is usually higher than ideal and becomes very difficult to change, but does not indicate that TA itself is a source of rising pH due to carbon dioxide outgassing. In the Spa & Therapy Operations section, when discussing pH, there is a discussion of aeration and carbon dioxide outgassing causing the pH to rise (and it says the TA decreases which is incorrect; the TA only drops when acid is added as acid lowers both pH and TA). However, even in this discussion it is not made clear that this effect can be reduced by lowering the TA level and supplementing pH buffering with a different non-carbonate pH buffer such as borates.

    Net pH of Hypochlorite Sources of Chlorine
    Hypochlorite sources of chlorine (bleach, chlorinating liquid, Cal-Hypo, lithium hypochlorite) are close to pH neutral when accounting for chlorine usage/consumption, except for the excess lye in some bleach and chlorinating liquid. This is described technically in this post. 6% Clorox Regular bleach has a very small amount of excess lye in it (pH 11.9 which implies 0.06% excess lye) so is very close to pH neutral when accounting for chlorine usage/consumption. Off-brand Ultra bleaches have a fairly high amount of excess lye (pH 12.5 or higher and 0.25% excess lye or higher). Chlorinating liquid varies, though even the best has a moderate amount of excess lye. Nevertheless, 12.5% chlorinating liquid with a pH of 12.5 and 0.25% excess lye (such as found here) results in a pH rise of around 0.1 unit per month assuming 2 ppm FC per day chlorine usage (so quite manageable). Chlorinating liquid closer to a pH of 13.0 has around 0.8% excess lye so over 3 times the pH rise rate or nearly 0.1 unit per week. Except for the high excess lye cases, the bulk of actual pH rise is usually due to carbon dioxide outgassing.

    The handbook is misleading in terms of the net pH of disinfectants since only the effect on pH of addition of the disinfectant is discussed. There is no discussion about how chlorine consumption/usage is acidic which makes the net pH of most hypochlorite sources of chlorine closer to pH neutral and makes Dichlor net acidic. The only net pH rise over time from hypochlorite sources of chlorine comes from any "excess lye" in them, which is minimal in 6% Clorox Bleach and is low in some chlorinating liquid (though is higher in other chlorinating liquid and in many off-brand bleaches).

    True Cost of Different Chlorine Sources
    Trichlor is not the least expensive source of chlorine when accounting for pH adjustment as described in this post. Bleach is often the least expensive source though Cal-Hypo and chlorinating liquid are sometimes close, though this varies a lot by region. Many people just look at the % Available Chlorine thinking that a higher number is a better value, but this is just a weight % of available chlorine and the price per pound of chlorinating liquid and bleach are very low (since it's mostly water) -- it is the price per increase in Free Chlorine (FC) that is what matters.

    The handbook does not discuss the costs of chlorine sources (except noting that lithium hypochlorite has a relatively high cost) nor the costs of pH adjustment for some of these sources.

    Breakpoint Chlorination
    The 10x rule for breakpoint chlorination is wrong and only now some industry people are starting to address this as described here and here, though they are still only accounting for the mistake of not considering that combined chlorine already used up a chlorine atom in combining with ammonia and they are not yet considering that there is still a factor of 5 error in their approach since the units used to derive the 10x rule come from chlorine (measured in ppm Cl2) oxidation of ammonia (measured in ppm N) whereas combined chlorine is measured in the same units as chlorine (i.e. ppm Cl2) where the Cl2 units are 5 times higher than the N units (that's the molecular weight ratio between the two). The oxidation of a combined chlorine that is monochlorourea (i.e. chlorine combined with urea) may require 3x, but that still far from 10x. There also isn't any getting "stuck" -- one can just add more chlorine. When one has persistent CC, it is not due to getting "stuck" but from compounds that do not oxidize as quickly. More technical details about this are described in this post.

    The handbook has a newer breakpoint chlorination rule, but it is still a "10x" rule, though uses a target FC as 10x of the CC rather than using an incrementally added 10x amount. It incorrectly states that adding less than the breakpoint calculated amount may not achieve breakpoint, not recognizing that the 10x rule is wrong when starting with CC (it's correct when starting with ammonia measured in ppm N units).

    Shocking a Pool
    In a residential pool with typically low bather load, it is not necessary to shock the pool regularly if the appropriate FC/CYA ratio is consistently maintained. Oxidation of bather waste occurs continuously and the Combined Chlorine (CC) is usually <= 0.5 ppm, often <= 0.2 ppm. Shocking is normally done in pools that use stabilized chlorine because their CYA climbs making the chlorine less effective so they need to shock to accelerate the oxidation of bather waste (which is slower due to lower active chlorine concentration) and to kill nascent algae growth. Shocking should only be done if there is an unusual event such as very high bather load, vomit, urine, diarrhea, dead animal, etc. or if the CC > 0.5 ppm (usually from excessive pollen or other organic matter that has entered the pool). As noted above under breakpoint chlorination, nothing gets "stuck" by not shocking the pool; shocking merely increases the active chlorine level to accelerate the rate of oxidation (and sanitation). So long as there is measurable FC, there is oxidation and sanitation occurring though possibly at a slower rate depending on the FC/CYA ratio. Indoor pools (even residential ones with low bather load) are more likely to get persistent CC and usually supplemental oxidation (UV, ozone, non-chlorine shock, enzymes) is needed to address this problem. It is possible that the UV in sunlight helps to prevent CC buildup in outdoor pools and is usually enough, along with normal active chlorine levels, to prevent significant CC in residential outdoor pools.

    The handbook talks about shocking as an oxidation process to remove contaminants, but does not prescribe a specific schedule.

    Attaining pH Stability, especially for SWG pools
    On this forum, we have figured out, through both theory and experiments and actual usage in real pools (and spas), how to make the pH nearly stable in most pools, including those using saltwater chlorine generators (SWGs). We did this in SWG pools not only by lowering the TA level, but also by targeting a higher CYA level of 80 ppm and by using 50 ppm Borates to reduce chlorine demand and let one turn-down the SWG on-time. We also figured out how 50 ppm Borates helps to prevent scaling in salt cells and possibly reduce the "white stuff" effect when using The Liquidator.

    The handbook does not talk about the specific challenges of pH rise in SWG pools, nor the solutions for this described above (lower TA, higher CYA, use of Borates).

    High Chlorine Demand and Chlorine "Lock"
    We figured out the mystery of unusually high chlorine demand, particularly upon spring opening after a pool has been "let go", even if the water is clear. Some bacteria can convert CYA into ammonia which creates a huge chlorine demand that can be calculated by measurements as described in this post. For every 10 ppm CYA that is degraded, it produces around 3 ppm ammonia that can take up to 30 ppm FC cumulatively added to eliminate. My personal experience of this effect is described in this thread. The myths of "chlorine lock" either from high CYA levels or from this conversion of CYA into ammonia are no longer mysteries, but known effects that can be understood, measured, and readily dealt with due to our increased knowledge.

    The handbook does not talk about this particular problem of opening a pool to unusually high chlorine demand from bacterial conversion of CYA to ammonia.

    Grocery/Hardware Store vs. Pool Store Chemical Equivalents
    We know that Arm & Hammer Super Washing Soda is identical to most pH Up products (both are sodium carbonate) and that Arm & Hammer Baking Soda is identical to Alkalinity Up products (both are sodium bicarbonate) and that 20 Mule Team Borax can be used to raise the pH with half the rise in TA and that Dowflake or Peladow or Tetra (de-icers) are identical to Calcium Hardness Increaser products (both are calcium chloride, though may be anhydrous vs. dihydrate), and that 6% Clorox Regular bleach has the lowest amount of excess lye in it resulting in a lower net pH rise over time than any chlorinating liquid from a pool store. More details on these products is in this post.

    The handbook does not talk about this topic.

    Procedures for Lowering TA
    There is also the acid column or slug method myth that was discredited in this paper. It's not that the method doesn't work at all, since the amount of TA lowering is solely dependent on the amount of acid you add and not how you add it, but rather that it is not the safest method (pooling acid in one area can damage plaster/vinyl surfaces) nor the most efficient (it can take longer for the pH to recover in time for you to add more acid to lower the TA some more). The efficient procedure for lowering TA (especially lowering the TA a lot) is described in this post and in the Pool School Lower Total Alkalinity procedure. The procedure works because the outgassing of carbon dioxide is accelerated at lower pH as shown in this chart.

    The handbook only says to add acid to lower the TA and does not discuss more efficient ways of lowering it via lowering the pH and increasing aeration (along with the acid addition).

    Phosphate Levels and Algae Control by Chlorine
    There is a myth of not being able to control algae by chlorine alone and that high phosphate levels must be lowered. Though phosphate levels do influence the rate of algae growth, phosphate removers only lower orthophosphate, not organic phosphates, so may not always completely stop algae growth and nitrates are also a limiting growth factor. Phosphate removers should be seen in the same vein as algicides that inhibit algae, but may not prevent it completely. Chlorine alone can be used to control algae if the FC/CYA ratio is above minimum levels (see chlorine/CYA chart described above).

    The handbook does not promote the use of phosphate removers, though does note that phosphates and nitrates are nutrients required for algae growth, but also notes the many different sources of phosphates (including storage in algae themselves). Various algicides are discussed with various pros and cons. The handbook notes that routine superchlorination and the use of an algicide on a maintenance basis are useful tools in the prevention of algae. However, there is no discussion of how chlorine alone, using a sufficient FC/CYA ratio, can prevent algae growth, though it is noted that it is very important that disinfectant residuals be maintained at all times to prevent the growth of algae.

    pH Effect on Chlorine When CYA is Present
    The presence of CYA acts as an active chlorine (hypochlorous acid) buffer making it much less susceptible to change at different pH. This is described in this post where one can see the traditional pH vs. chlorine graph and the true graph when CYA is present (this latter graph is not taught and it also shows the significantly lowered active chlorine level when CYA is present). When there is no CYA, going from a pH of 7.5 to 8.0 lowers the hypochlorous acid level by about 53% (from 1.45 to 0.69 ppm with 3 ppm FC), but with 30 ppm CYA it is only lowered by about 14% (from 0.042 to 0.036 ppm with 3 ppm FC).

    The handbook only shows a traditional chart of hypochlorous acid and hypochlorite ion vs. pH and does not show the effect of CYA as described above.

    CYA Protection of Chlorine from Sunlight
    CYA protects chlorine from degradation from the UV in sunlight in two different ways. At lower CYA levels, the main effect is having most of the chlorine bound to CYA where it degrades much more slowly. At higher CYA levels, especially noticed from 60-80 ppm, the CYA may shield lower depths from UV such that higher CYA levels at 70-80 ppm, even with correspondingly higher FC levels to keep the FC/CYA ratio constant, result in lower absolute chlorine loss. This is the main reason to have a high CYA level for outdoor SWG pools in order to reduce chlorine usage so that the SWG on-time can be lowered which results in a slower rate of pH rise (possibly due to less aeration and less undissolved chlorine gas outgassing).

    Commercial/public pools with moderate-to-high bather loads usually do not see any benefit of saved chlorine usage above a CYA level of 20-30 ppm, but this is primarily because most of the chlorine usage at these CYA levels is from bather load (oxidation of bather waste) so higher CYA levels would not result in a noticeable benefit. This is not the case with residential pools which typically have low bather loads such that degradation of chlorine by the UV in sunlight is a significant factor.

    The handbook does not discuss the varying apparent protection of CYA as a function of bather load.

    CYA and Indoor Pools and Any Spas
    Current industry recommendations and many state regulations say to not use any CYA in indoor pools or in any spas (at least commercial/public, though the most common chlorine source used in residential spas is Dichlor-only). This may be resulting in faster oxidation of swimsuits, skin and hair, faster corrosion, and higher levels of very irritating and volatile nitrogen trichloride as described in this post. Too much CYA is also a problem as the rate of oxidation is slowed too much so monochloramine and dichloramine can build up. 4 ppm FC with 20 ppm CYA for indoor pools may be a reasonable sweet spot for sufficient, but not too high, oxidation rates while lowering nitrogen trichloride production.

    The handbook does not discuss how CYA moderates chlorine's strength in ways as described above, though it does discuss (for spas) how dosing too much disinfectant may form more potentially toxic disinfection byproducts and may make bleaching of swimsuits and hair more likely.

    Turnover Rate and Law of Dilution
    [EDIT] NOTE: The 2014 edition of the handbook corrected the percentages to no longer use the inappropriate Gage and Bidwell Law of Dilution. [END-EDIT]

    The theoretical best-case model for continuous dilution of water has in one turnover all but e-1=0.368 or 37% of the water circulated, so 63% goes through the filter. In two turnovers this is all but e-2=0.135 or 14%, for three turnovers e-3=0.0497 or 5%, for four turnovers e-4=0.0183 or 2%. There is a model often quoted in the pool/spa industry called the Gage and Bidwell Law of Dilution that is misapplied to describe the amount of water seen by the filter. In fact, as described on PDF page 10 (paper page 1195) in this 1926 paper, this model is one where dirt or other contamination is introduced by bathers once a day (which in itself isn't very realistic) and the calculation is the percent clarification of pool water after equilibrium (steady-state) is obtained relative to the amount added per day. With this model, one turnover has 42% clarification so one pound of contamination per day would in the steady-state of one turnover per day have 0.58 pounds still in the water. With two turnovers, there is 84% clarification or 16% of the daily added amount left in the water. With three turnovers, there is 95% clarification or 5% left in the water. With four turnovers, there is 98% clarification or 2% left in the water. These clarification percentages are not the amount of water that "sees the filter" in one day. The reason the clarification percentages are lower than the percentages of water seen by the filter is that the model assumes regular introduction of additional contaminants each day and is a percentage of relative clarification, not the amount of water actually filtered per day.

    The handbook incorrectly uses the Gage and Bidwell Law of Dilution clarification percentages as a percentage of unfiltered water.
    [EDIT] NOTE: The 2014 edition of the handbook no longer uses the incorrect Gage and Bidwell Law of Dilution percentages. [END-EDIT]


    Acknowledgement and Further Info
    Much of this knowledge (at a high level) did not come from me or from this forum's outstanding members, though some has (I mostly contribute to the explanations using fundamental chemistry while many others contribute a wide variety of experience and technical knowledge in many areas). Ben Powell, who managed commercial and public pools, started PoolSolutions and The PoolForum and deserves a lot of credit for getting to the truth about many pool issues as well as helping thousands of pool owners. The rest of us are just following in his footsteps, extending and expanding the knowledge.

    For most of us on this forum, we maintain our pools using bleach or chlorinating liquid alone (or as the primary source of chlorine, unless an SWG is used) with perhaps a small amount of acid needed. That's it -- no algicides, no phosphate removers, no clarifiers or floculants, no regular shocking. In my own 16,000 gallon pool shown here and here, I only use around 1 ppm FC per day of 12.5% chlorinating liquid I get from my local pool store (they reuse the bottles, which is better than recycling) and even with a small amount of acid every month or so, it's around $15 per month in chemical costs (except for annual refreshing of calcium, some CYA and now borates after rain dilution over the winter). I have a mostly opaque electric safety cover, which helps keep the chlorine usage low, but the pool is used 1-2 hours every day during the week and longer on weekends. Oh, and did I mention that my pool has typically had 2000-3000 ppb and higher phosphates and averages 88F temperature yet does not get algae? Most people on this forum have similar experiences and many have had bad experiences with pool stores and pool services where it really isn't their fault because they are simply not taught the whole truth from manufacturers and industry courses. There are over 20,000 members at The PoolForum (which unfortunately is closed to new membership [EDIT] it is now open to membership, but reports around 16,000 members [END-EDIT]) and over 10,000 members here at Trouble Free Pool (and growing rapidly [EDIT] now over 72,000 [END-EDIT]) where we help each other out because we unfortunately do not get this kind of help from many (but not all) pool stores, though that will hopefully start to change as industry education improves.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: Certified Pool Operator (CPO) training -- What is not taught

    I just ordered a 2009 NSPF Pool & Spa Operator Handbook from NSPF so will update/correct the post above after I get the book, assuming that what is in the book is the same (in summary form) as what is taught in the CPO course.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: Certified Pool Operator (CPO) training -- What is not taught

    According to http://www.nspf.org/CPO_Courses.html the course is from the handbook plus local codes. (See the "Primer + Fusion vs 2-Day Class" tab.)
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    Re: Certified Pool Operator (CPO) training -- What is not taught

    A few quick thoughts, I just have a few minutes:

    They've changed the breakpoint calculation thing, it's now 10x minus whatever's present as opposed to just 10x.

    They make it a point to say that it is unlawful to use a product for a purpose other than one it is labeled for (or something to that effect) - so you'll never see a CPOI say you can use borax to increase pH for example. On the "residential" side people can do what they want but on the "public" (commercial) side this just makes a whole lot of sense.

    From what I can tell the jury is still out on the slug method for lowering TA, Taylor still has it in their book, it's still in the CPO book, European pool chem books describe it as well.

    The water chemistry/testing is just a small part of the whole CPO course, there's never enough time to go through all the book in depth anyways. And you see people's eyes glaze over when the subject of chemistry is approached so the instructors seem to skim quickly over that chapter (just covering the essential).

    There's no issues with CYA and ammonia because the public pools are drained and refilled upon opening.

    The chlorine costs are very much a regional consideration. Some places have cheap bleach, some places have cheap calhypo.

    I think you may be taking a course primarily designed for public pool operators and looking at it too much as a residential pool owner. They're two very different things.

    They talk about borates as a algistat only, not as a pH buffer.

    It's 0 ppm CYA for indoor installations, you deal with CC by educating the public on showering before entering the pool, and by various other methods (water "stripping" towers seems particularly effective).

    That's all for now, got to go, sorry for the unstructured post!

    Paul

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    Re: Certified Pool Operator (CPO) training -- What is not taught

    I received a purchased copy of the 2009 "CPO Handbook, National Swimming Pool Foundation" with front cover title "Pool & Spa Operator™ Handbook" and am very impressed with it. It is very detailed, in full color, and with many clear illustrations and examples. It is very clearly oriented towards commercial/public installations since the certification is, after all, for a pool operator, not for a pool store selling to residential pools or to a pool service servicing residential pools. Nevertheless, there are basic principles not covered or only partially covered in the book that I have outlined in the first post in this thread.

    My only other complaint with the book is that it appears to have been printed using inks that do not withstand rubbing with a finger due to a combination of pressure, heat and moisture (water alone doesn't seem to cause a problem). It behaves somewhat like an inkjet print or newsprint, even though the pages appear glossy. Given the use of this manual for reference, it would be better to have it printed using printing technology that would withstand smudging better.

    Though I have read through the entire book, my focus was on the chapters on "Pool Water Contamination", "Disinfection", "Water Balance", "Pool & Spa Water Problems", "Chemical Testing" and "Spa & Therapy Operations". I have 61 Post-It Notes on the pages in these chapters and plan to write a detailed document/E-mail with suggestions to send to NSPF, but for now have focused on correcting the first post in this thread to reflect what is truly in and not in the manual.

    Richard
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    Re: Certified Pool Operator (CPO) training -- What is not taught

    Paul,

    Thank you for your feedback. I wanted to wait until I received the CPO handbook before responding.

    I've updated the info on the newer breakpoint formula. Good point about product use based only on labeling. They don't talk about the "slug" or "acid column" method in the 2009 handbook. In the handbook, water chemistry and testing is discussed in various ways in 6 of the 18 chapters, but I see what you mean about it being just one part of the course and one that many people may find difficult. Good point about opened pools using fresh water. Also good point about regional chlorine costs. I've now noted the commercial/public vs. residential focus in my initial post. Yes, the handbook only refers to borates as an algistat and not for raising pH (from Borax) or as a pH buffer. The handbook only notes that CYA limits are regulated by state so does not say they must be 0 for indoor pools or for spas though that is the regulation in many states (for commercial/public pools/spas; no such regulations exist for residential pools/spas).

    Richard
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    Re: Certified Pool Operator (CPO) training -- What is not taught

    Richard,

    I'm currently reading through your report of suggestions for improvement to the Handbook.

    Regarding the raising of PH on Page 13 I notice that you have crossed out the use of sodium bicarbonate as a chemical to use for the raising of PH.

    It has always been my understanding that sodium bicarbonate is a good chemical to use to raise alkalinity but with the rider that is will also raise your PH.

    I can only assume that that you have taken this out because sole use as a PH+ product will have an adverse effect on your TA. But does the fact not remain that if you added Sodium Bicarbonates then the PH will rise.

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    Re: Certified Pool Operator (CPO) training -- What is not taught

    I think you have sodium carbonate and sodium bicarbonate mixed up. Sodium bicarbonate is baking soda, also called alkalinity increaser. PH Up products are sodium carbonate, also called soda ash or washing soda. Sodium bicarbonate raises PH just a little, and raises TA a lot. Sodium carbonate raises PH a lot, and raises TA just a little.

    Technically, the PH will go up when you add sodium bicarbonate (baking soda), however in normal situations it will take huge amounts of sodium bicarbonate to raise the PH any significant amount, which will raise your TA very dramatically.
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    Re: Certified Pool Operator (CPO) training -- What is not taught

    Quote Originally Posted by JasonLion
    I think you have sodium carbonate and sodium bicarbonate mixed up. Sodium bicarbonate is baking soda, also called alkalinity increaser. PH Up products are sodium carbonate, also called soda ash or washing soda. Sodium bicarbonate raises PH just a little, and raises TA a lot. Sodium carbonate raises PH a lot, and raises TA just a little.

    Technically, the PH will go up when you add sodium bicarbonate (baking soda), however in normal situations it will take huge amounts of sodium bicarbonate to raise the PH any significant amount, which will raise your TA very dramatically.
    Jason,

    No mixing up at all.. I fully understand the difference between the the two sodiums. Richard clearly has crossed out the Sodium bicarbonate from his recommendations in the suggested changes to the manual and I'm enquiring why.. It appears from what you have said that it confirms my suspicions as the reason why, whilst sodium bicarbonate will raise the PH it will only do so much to the detriment of the TA and would explain why he crossed it off the list. I personally only ever use Sodium bicarbonate to raise TA and only when my PH is below 7.8 because I always seem to get at least 0.1 raise in PH when I do use it.

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    Re: Certified Pool Operator (CPO) training -- What is not taught

    Just an FYI.....
    The latest Code from the state of Texas clearly mandates a 0 ppm level of CYA for indoor pools and a 50 ppm max for outdoor commercial/public pools. Obviously this varies from state to state. My point being, everyone should follow the guidelines for your state or city above anything the CPO manual says. The code also states that water features and spray pads must be maintained as pools and spas now.
    I'm glad I don't have to deal with this as we've never used any type of stabilized chlorine in our indoor pools but, I can see how trying to maintain 50ppm in an outdoor pool would be tough.

    I'm glad to read your opinions on the TDS levels especially on pools with SWGs. Our commercial SWGs require a 4800 to 5200 ppm salt level so, as you can imagine calculating TDS levels correctly is next to impossible.
    I would like to factor in TDS when calculating Saturation Index but it's not feasible in our setup.

    The CPO course is worth taking by all means, I wished it were more in depth in some instances. A lot of the folks who I meet in these classes tend not to know anything about pools and this is their very first lesson of any type regarding pools and spas. A lot of times hotels and apartment complex send people to get certified that might be the painters or the A/C person and really aren't even too interested in pools. Nothing wrong with this but, in my opinion the CPO course might at least cover an actual water testing demo for these folks.
    Just had to re-up my CPO in May and met several folks who had no idea what VGB even stood for. They obviously could have used a more comprehensive education to help them out.

    BTW, I don't disagree with you about a small level of CYA being fine in an indoor pool. I've actually tried it based on your advice. I've been informed that our SWG units advise against any level of CYA though. I'm not even sure I know the reasoning but, since I have a 0 level it wasn't worth questioning.

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    Re: Certified Pool Operator (CPO) training -- What is not taught

    Quote Originally Posted by Freelancer
    Richard,

    I'm currently reading through your report of suggestions for improvement to the Handbook.

    Regarding the raising of PH on Page 13 I notice that you have crossed out the use of sodium bicarbonate as a chemical to use for the raising of PH.

    It has always been my understanding that sodium bicarbonate is a good chemical to use to raise alkalinity but with the rider that is will also raise your PH.

    I can only assume that that you have taken this out because sole use as a PH+ product will have an adverse effect on your TA. But does the fact not remain that if you added Sodium Bicarbonates then the PH will rise.
    Sodium bicarbonate mostly raises the TA level, but it can also raise the pH depending on 1) how low the pH starts out and 2) how the sodium bicarbonate is added. When sodium bicarbonate is added quickly so that it concentrates near the surface of the water, you can even notice it bubbling somewhat which is carbon dioxide outgassing due to the locally high TA level. So the pH can rise with sodium bicarbonate, but the amount that it does so is not reliable. Therefore, I think it is better to recommend using sodium carbonate / washing soda or borax (or even sodium hydroxide / caustic soda / lye) for raising pH while leaving sodium bicarbonate for raising TA. When added slowly and dispersed quickly, the rise in pH is fairly low unless the starting pH is low.
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    Re: Certified Pool Operator (CPO) training -- What is not taught

    Quote Originally Posted by subslug
    Just an FYI.....
    The latest Code from the state of Texas clearly mandates a 0 ppm level of CYA for indoor pools and a 50 ppm max for outdoor commercial/public pools. Obviously this varies from state to state. My point being, everyone should follow the guidelines for your state or city above anything the CPO manual says. The code also states that water features and spray pads must be maintained as pools and spas now.
    I'm glad I don't have to deal with this as we've never used any type of stabilized chlorine in our indoor pools but, I can see how trying to maintain 50ppm in an outdoor pool would be tough.
    :
    :
    BTW, I don't disagree with you about a small level of CYA being fine in an indoor pool. I've actually tried it based on your advice. I've been informed that our SWG units advise against any level of CYA though. I'm not even sure I know the reasoning but, since I have a 0 level it wasn't worth questioning.
    While obviously commercial/public pools must follow local/state codes or else they are in violation of the law, I still have the opinion that the no CYA rule for indoor pools is based on misinformation. It primarily comes from the chlorinated cyanurate manufacturers only emphasizing CYA's role in reducing chlorine loss from sunlight and downplaying its role as a chlorine buffer significantly reducing the active chlorine concentration. No one, and I mean no one, talks about the order-of-magnitude (usually 10x) difference in active chlorine concentrations between indoor pools with no CYA vs. outdoor pools with CYA and the implications on oxidation rates of swimsuits, skin and hair, on metal corrosion, and on the rate of production of nitrogen trichloride. The PPOA organization does talk about the high oxidation rates and ORP levels when CYA is zero but only tout this as a good thing and ignore the negative implications.

    I suspect the SWG units you are talking about that recommend against CYA have ORP controllers. ORP controllers have a hard enough time properly controlling chlorine levels when the active chlorine level is high (i.e. when the ORP is high) and don't do as well when these levels are lower which they would be when there is CYA. However, they should do alright at the level I recommend of 4 ppm FC with 20 ppm CYA which is equivalent in active chlorine level to around 0.2 ppm FC with no CYA. Their blanket recommendation is more to prevent situations like 2 ppm FC with 50 ppm CYA which would be much harder to control being more like 0.04 ppm FC with no CYA.
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    Re: Certified Pool Operator (CPO) training -- What is not taught

    I suspect the SWG units you are talking about that recommend against CYA have ORP controllers. ORP controllers have a hard enough time properly controlling chlorine levels when the active chlorine level is high (i.e. when the ORP is high) and don't do as well when these levels are lower which they would be when there is CYA.
    I find ORP controllers to be a constant battle. They're a fact of life for me but, anyone who thinks putting in an ORP to help automate their system is going to make their life easier has a rude awakening ahead of them.
    We've upgraded to ORP probes with gold tips and it helps a lot but it's still not perfect. I find it funny that every pool person who I've dealt with sells a controller that's the greatest thing ever.

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    Re: Certified Pool Operator (CPO) training -- What is not taught

    Chem Geek,
    I am a little confused. In your post in this thread you state
    "For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6.1 ppm"

    Now my confusion surrounds the use of the term Cyanuric Acid. Do you really mean the total cyanurates added or do you mean what you say, namely the species (H3CYA)? I would have assumed you meant the total cyanurates in whatever stage of chlorination that they are in (H3CYA, ClH2CYA, Cl2HCYA, Cl3CYA and the ionized forms). This would be a useful number since the potential total reservoir of chlorine available for sanitation is proportional to the total cyanurate concentration.

    By free Chlorine (FC) I assume you mean all the forms of chlorine that will test positive for chlorine on some chemical test (DPD or OTO) and you have asserted elsewhere in your post that all chlorine (atoms), HOCL, OCL-, and all chlorinated cyanurates will contribute to the chlorine tested (it would be good to have a reference to experimental work here). OK then. If I add one molecule of Trichlor I will get 3 atoms of Chlorine that will be counted in a test and one of molecule of CYA in some form, (H3CYA, ClH2CYA, Cl2HCYA, Cl3CYA and the ionized forms). If this is the case your statement is in error. There will be 10 ppm of FC for 3.3 molecules of CYA (in all its forms) released from 3.3 molecules of Trichlor (Cl3CYA - just look at the formula, 3 Cl to one CYA). Since pool chemistry is new to me (just look at my pool if you have any doubts), what am I missing?
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    Re: Certified Pool Operator (CPO) training -- What is not taught

    You're making the same mistake I did when I first started thinking about this
    FC is measured as ppm Cl2, not ppm Cl-. There's a little more to it than that though. You have to take the fraction of the molecular weight of trichlor that is composed of Cl, then essentially divide by 1.5 to convert that Cl to Cl2. Actually, rather than trying to explain it myself, here's the thread where Richard (chem geek) explained it to me:
    fc-cya-ratios-in-dichlor-and-trichlor-wait-am-i-a-moron-t20537.html

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    Re: Certified Pool Operator (CPO) training -- What is not taught

    Melt in the Sun
    Thanks for the link. The confusion (at least mine) is with the definition of ppm but the discussion at the link you provided makes it clear that we are dealing with weight ratios with the added twist of equivalency to oxidizing power of Cl2.

    However, the second part of my post asked if anyone knows of a study that showed that trichlor does indeed produce the correct result for ppm Cl2 in an indicator test (DPD or OTO). Though now armed with the correct definition of ppm I can probably run this test myself, but it would be more satisfying if it were reported from a real chem lab in a refereed journal - probably many decades ago. Thanks again.
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    Re: Certified Pool Operator (CPO) training -- What is not taught

    Quote Originally Posted by 20dollars
    but it would be more satisfying if it were reported from a real chem lab in a refereed journal - probably many decades ago. Thanks again.
    This is way too trivial for a refereed journal, it would never get published. You can derive the result from the chemical formula for trichlor in under a minute if you know the molecular weights and what units are being used. Likewise anyone with a reasonably precise FC test (for example the FAS-DPD chlorine test) can confirm the FC portion of the result in a real pool in under an hour.
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    Re: Certified Pool Operator (CPO) training -- What is not taught

    Quote Originally Posted by 20dollars
    Now my confusion surrounds the use of the term Cyanuric Acid. Do you really mean the total cyanurates added or do you mean what you say, namely the species (H3CYA)? I would have assumed you meant the total cyanurates in whatever stage of chlorination that they are in (H3CYA, ClH2CYA, Cl2HCYA, Cl3CYA and the ionized forms). This would be a useful number since the potential total reservoir of chlorine available for sanitation is proportional to the total cyanurate concentration.
    I think I missed answering this particular question. When I wrote CYA, I mean in all forms.

    The CYA test has melamine combine with CYA to form a precipitate, especially at lower pH which forces most of the CYA forms to the CYA acid as opposed to ionized forms. As far as the chlorinated cyanurates go, there's some debate about that where some have said that at high chlorine levels one needs to dechlorinate the water sample first before doing the CYA test, presumably because the chlorinated cyanurates do not form the melamine complex to precipitate. However, in practice, experiments done by a few on this forum indicated that this wasn't a problem. My guess is that at the normal FC/CYA ratios used in most pools even at shock level, the most dominant form is still HClCY- (where "CY" represents the CYA core ring) and where at the low pH in the CYA test the dominant chlorinated cyanurate is H2ClCY and that this is able to complex with melamine since the chlorine can be on "the other side" of the ring and not interfere with the hydrogen bonds (see this picture of the melamine-cyanurate complex).

    So the bottom line is that the CYA test essentially measures all of the CYA in all forms including that found as chlorinated cyanurates.
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    Re: Certified Pool Operator (CPO) training -- What is not taught

    as far as the breakpoint calcuation, it has become very unclear between different editions. The best description/explanation I have read is on Robert Lowry's Pool Chlorination Facts where he talks about multiplying the combined chlorine by 7.6 to determine the correct amount of FAC to add to reach breakpoint. Dr Lowry's books can be purchased on his website http://www.lowrycg.com/book.php

    We can all make suggestions to the NSPF by emailing tom.lachocki@nspf.org . He is the CEO, and a very good one at that.
    Sincerely,

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    Re: Certified Pool Operator (CPO) training -- What is not taught

    I think Lowry came up with the concept that your FC should be 10% of your CYA.

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