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Thread: Can't get cc down

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    Can't get cc down

    OK so last night measurd water

    Fc .5
    Cc 2.5
    Ph 7.5
    AK 60
    Borate 50
    Cya 50
    Ch140

    Added chlorine to bring up to 16ppm and added 66ml mps ran with cover off for 1 hour

    Tonight

    Fc 8
    Cc 2.5
    Mps not sure reading was with 10ml sample 21 with mps reagent so 10.5 tc

    Then measured again without mps reagent
    15 so 7.5?

    Why is my cc not coming down
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

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    Mod Squad Texas Splash's Avatar
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    Re: Can't get cc down

    Sounds like you're on the verge of an algae bloom and should "maintain" the elevated FC level as noted in the SLAM instructions. So with a CYA of 50, you'll want to increase FC to "20" and keep it there. FIRST - lower pH to 7.2, then increase the FC. Test frequently at first - every 1-2 hours, then maintain it until you pass all 3 SLAM criteria. Leave the cover off as much as you can during this process so the pool can breathe and the sun can oxidize the CC for you. Hopefully with the cover off and increased FC it won't take too long, but maintain an FC of 20 until you pass all 3 criteria.

    After you pass, increase CYA to 70 - minimum for a SWG pool. Have a nice weekend.
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    Isaac-1's Avatar
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    Re: Can't get cc down

    MPS shows as CC on the common chlorine tests, Taylor makes a special MPS elimination test, but it is expensive (around $50 I think) this is part of why MPS is not part of the TFP method
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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    Re: Can't get cc down

    It is my spa

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    JoyfulNoise's Avatar
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    Re: Can't get cc down

    To be clear - MPS shows up as excess FC on the DPD-FAS titration test (R-0870 & R-0871) and it shows up as CCs on the DPD only test (R-0001/R-0002 & R-0003).

    It only shows up as CC on the FAS-DPD test IF the FC level is zero.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: Can't get cc down

    Hmm then why do8ng my dad fast test I got less fc when not adding mps reagent

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    Re: Can't get cc down

    You raised the FC to 16 and ended up with 8. Where did the other 8ppm FC go? It probably reacted with all the nitrogen rich bather waste in the tub and created more Chloramines. Chloramines will show up as CC. If you ran the tub with the top open, you drove out a bunch of the Chloramines through aeration, which brought the CCs right back to where they started.

    So you basically converted a bunch of FC to CC and then got rid of a bunch of CC so all you saw was a drop in FC while CC appeared to stay the same.
    TreeFiter

    Pool Technician
    Saugerties, NY

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    Re: Can't get cc down

    I thought whenot you added mps and shocked you want the games to burn off to reduce cc

    So what should I do

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    Isaac-1's Avatar
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    Re: Can't get cc down

    huh?
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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  10. Back To Top    #10
    MarianParoo's Avatar
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    Re: Can't get cc down

    Quote Originally Posted by JoyfulNoise View Post
    To be clear - MPS shows up as excess FC on the DPD-FAS titration test (R-0870 & R-0871) and it shows up as CCs on the DPD only test (R-0001/R-0002 & R-0003).

    It only shows up as CC on the FAS-DPD test IF the FC level is zero.
    Great post!
    27K IG rectangular; vinyl liner; sand filter; 1hp pump; auto-cover; heater; K-2006C.

  11. Back To Top    #11

    Re: Can't get cc down

    Quote Originally Posted by Isaac-1 View Post
    huh?
    Stupid auto correct changes most of what I type
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

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    Mod Squad kimkats's Avatar
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    Re: Can't get cc down

    Quote Originally Posted by outdoor View Post
    Stupid auto correct changes most of what I type
    Please go back and do an edit to make it easier to read and understand.

    THANKS!
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit, Become a TFP supporter!

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    Re: Can't get cc down

    Quote Originally Posted by outdoor View Post
    I thought whenot you added mps and shocked you want the games to burn off to reduce cc

    So what should I do
    Yes, by adding an oxidizer you are trying to burn off all the nasties in your tub. MPS and Chlorine both serve that purpose. If there are a lot of nasties in the tub to burn off, you will need to add more.

    You raised the FC to 16 and added some MPS. If you used up half of the chlorine you added, and still have 2.5 CC, you need to add more. As pointed out by others, MPS is tricky to test for because it shows up as CC on some tests, which essentially makes that test useless as there is no way to know what that test is actually telling you.

    It is also possible that the measuerement for CC you are now seeing is actually a measurement of MPS. If you burned off everything, only the MPS would be left to show up as CC. Watch your FC. If it continues to drop without the tub being used, there are more nasties waiting to be burned off. If it remains stable, your CC measurement may actually be how much MPS is left.

    Is there a reason you are using both Chlorine and MPS? Why not just use chlorine. A bottle of bleach is about 1/10 the cost of a container of MPS.
    TreeFiter

    Pool Technician
    Saugerties, NY

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    Re: Can't get cc down

    Cc (trichloramines) elimination requires daily supershocking(twice as much as you would put in normally to raise FC from a zero ppm to 3 ppm) and running the system continuously until the cc disappears. It usually takes 3-4 days for a standard 15-20k pool to eliminate the trichloramines using this method. Make sure your pH is around 7.6 as this daily supershocking will drop your pH levels and ensure that the TA is 70-90 to maintain pH consistency. As for cyanuric acid.... It's a spa with a cover... There's no real need to have CA in the tub unless u left it open throughout the day.

    Cyanuric acid is there to prevent direct sunlight from destroying chlorine from exposure. If a cover is on most of the time, there's no need for a high level of cyanuric acid as some have suggested. 20-30 ppm will suffice for a spa/hot tub either way.

    Sent from my SM-G925P using Tapatalk

  15. Back To Top    #15

    Re: Can't get cc down

    Still having a problem.

    I've raised my Chlorine to 17ppm and above for about 36 hours. As well last night, i added 2 oz of MPS. Opened the cover and left it for 2 hours.

    Prior to adding MPS and opening cover, I still had cc of around 2.5ppm.

    I will test again tonight, but it seems i'm having a very hard time getting rid of the cc.

    I only got my hot tub on Sept 1st. Brand new

    Prior to using, i filled and ran Ah Some cleaner through

    I've added:

    Spa Marvel (thinking this would greatly reduce Chlorine usage)
    Spa Boss Ultra Spa Water Conditioner (borates)
    Calcium
    CYA

    So since then my readings have been

    ph around 7.6-7.8 (sometimes higher, when i was working on lowering TA and pH)
    TA around 70
    CYA around 50 ( i know some have said it does not need to be this high) Will keep this in mind when i refill next time
    CH 140
    Borates 50

    I do not have any ozonator

    My spa has 2 filters. A micron filter and then regular. I rinsed every 2 weeks and then on Oct 1st took old ones cleaned in Muriatic acid solution left to dry and put in 2 new ones

    So, i'm unclear why my cc is still 2.5ppm

    The other issue is since I've been shocking the last few nights, we can't use it.

    How much MPS is too much? What does my Chlorine need to be if I've added MPS to reduce CC and still use it?

    I do have the Taylor reagent that is supposed to eliminate MPS impact on Chlorine test.

    I'm also going through a bunch of reagent doing the tests. Particularly if i have to eliminate the MPS since i have to use 25ml sample instead of 10ml so that means using many more R0870 drops. If my chlorine is at 20ppm, that is like 100 drops
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  16. Back To Top    #16

    Re: Breakpoint Chlorination

    Quote Originally Posted by chem geek View Post
    Breakpoint chlorination is very real, but as I wrote in my post the 10x rule-of-thumb that comes from it was misapplied to swimming pools with regard to getting rid of Combined Chlorine (CC). The link you gave to a presentation doesn't even go into the same level of detail as I do (in other posts) and doesn't even talk about the 10x part of breakpoint chlorination that is the part that is misapplied to CC in the pool industry. The presentation also has graphs showing chlorine concentration/effectiveness that do not apply when Cyanuric Acid (CYA) is in the water (i.e. the "Free Chlorine Distribution with pH" graph doesn't apply when CYA is present and I show the proper graphs in this post).

    So let's take this step-by-step and walk you through this. First of all, let's go through where breakpoint chlorination and specifically the 10x rule comes from since much of that information is not in the presentation you linked to. More detail is in the thread Chloramines and FC/CYA. It comes from adding chlorine to ammonia where initially there is more ammonia then there is chlorine. That is not a normal situation in swimming pools where chlorine levels are maintained and there is usually much more chlorine than ammonia. Nevertheless, the first step is the following:

    (1) HOCl + NH3 ---> NH2Cl
    Hypochlorous Acid + Ammonia ---> Monochloramine

    The above reaction occurs very quickly with 95% completion in a few seconds when no CYA is present or under a minute when CYA is present. By the way, in that presentation you linked to on the page entitled "How fast is chloramine formation?" it uses as an example for rates an HOCl concentration of 0.2x10-3 mol/l, but did you actually calculate how much this is? It's 14.2 ppm (mg/L) with no CYA which is quite high. That's why he gets 0.2 seconds at a pH of 7. In practice the levels are lower which is why I quote a few seconds for 95% completion, but the point is still the same that the above reaction is rather fast. If you were to open a pool with ammonia in it, you would find that the chlorine demand is very rapid and forms CC with no resulting FC, but that is NOT the situation in pools maintaining chlorine and having a bather load and it is not the situation described by the original poster in this thread where they already are measuring FC so clearly there is not ammonia remaining in the pool. So that brings us to the next series of equations that are much slower than the above.

    (2) HOCl + NH2Cl ---> NHCl2 + H2O
    Hypochlorous Acid + Monochloramine ---> Dichloramine + Water

    (3) HOCl + NHCl2 ---> NCl3 + H2O
    Hypochlorous Acid + Dichloramine ---> Nitrogen Trichloride + Water

    (4) NHCl2 + NCl3 + 2H2O ---> 2HOCl + N2(g) + 3H+ + 3Cl-
    Dichloramine + Nitrogen Trichloride + Water ---> Hypochlorous Acid + Nitrogen Gas + Hydrogen Ion + Chloride Ion

    The full set of Jafvert & Valentine equations including the above are in this Breakpoint spreadsheet I made. Initially, equation (1) dominates and is the fastest so monochloramine is produced. Then equation (2) grows in speed and dominates (because the monochloramine builds up and the ammonia declines) and equation (3) then occurs as well and then (4) so that all three equations (2,3,4) run together so that there is not a lot of dichloramine or nitrogen trichloride lasting very long as intermediates but this process takes around 10 minutes when no CYA is present (more than 90% complete with 2 ppm FC) or around 4 hours when CYA is present (with FC/CYA ratio 7.5%).

    The net reaction, ignoring some side reactions that go to nitrate, is the following

    3HOCl + 2NH3 ---> N2(g) + 3H2O + 3H+ + 3Cl+
    Hypochlorous Acid + Ammonia ---> Nitrogen Gas + Water + Hydrogen Ion + Chloride Ion

    You can see that there is a molar relationship of 3:2 for chlorine to ammonia. Chlorine is measured in ppm Cl2 units where molecular chlorine has a molecular weight of 70.906 g/mole whereas ammonia is measured in ppm N units where atomic nitrogen has a molecular weight of 14.0067 so in terms of a chlorine to ammonia ppm (weight) ratio it is (3*70.906)/(2*14.0067) = 7.593. In practice due to side reactions producing nitrate, the actual weight ratio needed for chlorine oxidation of ammonia is 8 to 10 and this is where the 10x rule-of-thumb comes from.

    Now let's look at how this very valid rule was misapplied in the pool industry. The pool industry took this rule and applied it against Combined Chlorine (CC). The first major flaw is that CC is measured in molecular chlorine units (i.e. ppm Cl2), NOT ammonia nitrogen units (i.e. ppm N). So there is no factor of 70.906/14.0067 = 5.062 weight difference. The second major flaw is that CC already has chlorine combined with ammonia presuming it is mostly monochloramine which should be the case if one starts with ammonia. So two of the 3 initial chlorine would have already been used up combining with the two ammonia. In other words, when starting with CC that is monochloramine, the net reaction is the following:

    HOCl + 2NH2Cl ---> N2(g) + H2O + 3H+ + 3Cl+
    Hypochlorous Acid + Monochloramine ---> Nitrogen Gas + Water + Hydrogen Ion + Chloride Ion

    So the molar ratio of what is left is only 1:2, not the original 3:2. In practice it would take a little more than this 0.5 amount, but the point is that it is nowhere near the presumed 10x rule.

    Even if one goes through this same analysis using chlorination of urea one doesn't get to more than 3x at the most. The 10x rule is completely wrong in its application to CC because 1) the unit of measurement of CC is 5 times larger than that of ammonia so takes 1/5th as much chlorine compared to ammonia and 2) chlorine is already part of CC so it takes less chlorine to further oxidize it.

    Finally, in pools breakpoint chlorination is continuous because chlorine levels are maintained. So there is no magic number whether it be 10x or 3x or 1x because one is not asking how much chlorine is needed to complete oxidation but rather is simply asking whether increasing chlorine concentration will make things go faster and make things better or worse. That's what I responded to in my post. Increasing chlorine concentration can have the CC decrease if the original chemical to be oxidized was ammonia, but the CC may increase if the original chemical to oxidize is urea because urea is much slower to combine with chlorine. There are other techniques for removal of organics precursors such as urea including flocculation/coagulation that may be more effective and of course supplemental oxidation (e.g. ozone) may be helpful.

    Where the breakpoint chlorination of chlorine added to ammonia does apply is when opening a pool in the spring to a huge chlorine demand when bacteria have converted CYA into ammonia (see Degradation of Cyanuric Acid (CYA)) where one can use an ammonia test kit to see how much ammonia is left to oxidize and here one can legitimately use the 10x rule-of-thumb to figure out how much more chlorine (FC) one needs to add to oxidize such ammonia. Note that one only uses this 10x rule multiplying the ppm N (or ppm NH3 which is close enough) from an ammonia test kit and NOT the CC amount if one already started adding chlorine since CC is in ppm Cl2 units and already has one chlorine attached to ammonia as monochloramine. However, in such degradation of CYA this will be an underestimate of the amount of chlorine needed since there is often partially degraded CYA still left (e.g. biuret, allophanate) and that doesn't show up in ammonia tests nor as CC.


    So if my Spa has 2.5ppm CC how much MPS do i need to add without adding much more Chlorine to get rid of cc?
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  17. Back To Top    #17

    Re: Can't get cc down

    Quote Originally Posted by outdoor View Post
    Still having a problem.

    I've raised my Chlorine to 17ppm and above for about 36 hours. As well last night, i added 2 oz of MPS. Opened the cover and left it for 2 hours.

    Prior to adding MPS and opening cover, I still had cc of around 2.5ppm.

    I will test again tonight, but it seems i'm having a very hard time getting rid of the cc.

    I only got my hot tub on Sept 1st. Brand new

    Prior to using, i filled and ran Ah Some cleaner through

    I've added:

    Spa Marvel (thinking this would greatly reduce Chlorine usage)
    Spa Boss Ultra Spa Water Conditioner (borates)
    Calcium
    CYA

    So since then my readings have been

    ph around 7.6-7.8 (sometimes higher, when i was working on lowering TA and pH)
    TA around 70
    CYA around 50 ( i know some have said it does not need to be this high) Will keep this in mind when i refill next time
    CH 140
    Borates 50

    I do not have any ozonator

    My spa has 2 filters. A micron filter and then regular. I rinsed every 2 weeks and then on Oct 1st took old ones cleaned in Muriatic acid solution left to dry and put in 2 new ones

    So, i'm unclear why my cc is still 2.5ppm

    The other issue is since I've been shocking the last few nights, we can't use it.

    How much MPS is too much? What does my Chlorine need to be if I've added MPS to reduce CC and still use it?

    I do have the Taylor reagent that is supposed to eliminate MPS impact on Chlorine test.

    I'm also going through a bunch of reagent doing the tests. Particularly if i have to eliminate the MPS since i have to use 25ml sample instead of 10ml so that means using many more R0870 drops. If my chlorine is at 20ppm, that is like 100 drops
    So retested my water tonight.

    TC 17ppm
    CC 2.5ppm

    added more MPS, ran with cover open. all jets with air on for 3 cycles of 20 min and overall cover open for about 2 hours

    retested

    TC 18ppm
    cc 2.5ppm - 3 ppm

    bascially unchanged. no change from 24 hours ago either.

    ??
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  18. Back To Top    #18
    Mod Squad pooldv's Avatar
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    Re: Can't get cc down

    MPS does not break down CC and will also test as CC. Chorine and sunshine break down CC.

    This is from here, Pool School - Definitions and Abbreviations
    Potassium Monopersulfate
    Potassium Peroxymonosulfate
    A non chlorine oxidizer or 'shock'. It is acidic and will cause lower pH and TA. It adds sulfates to the water. Will not break down CC but helps prevent it from forming when used on a regular basis. It will interfere with TC and CC tests unless special reagents are used in testing since it WILL test as CC! A good choice to use in indoor pools that are not exposed to sunlight but really has no advantage in an outdoor pool. It is only an oxidizer and NOT a sanitizer and should not be used as such.
    TFP Moderator
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  19. Back To Top    #19

    Re: Can't get cc down

    Quote Originally Posted by pooldv View Post
    MPS does not break down CC and will also test as CC. Chorine and sunshine break down CC.

    This is from here, Pool School - Definitions and Abbreviations
    Potassium Monopersulfate
    Potassium Peroxymonosulfate
    A non chlorine oxidizer or 'shock'. It is acidic and will cause lower pH and TA. It adds sulfates to the water. Will not break down CC but helps prevent it from forming when used on a regular basis. It will interfere with TC and CC tests unless special reagents are used in testing since it WILL test as CC! A good choice to use in indoor pools that are not exposed to sunlight but really has no advantage in an outdoor pool. It is only an oxidizer and NOT a sanitizer and should not be used as such.
    It should not test as CC if I'm using the R0867 reagent though correct? It is supposed to eliminate MPS impact.

    So if my Chlorine is basically not dropping, why is cc not going away? Does that not indicate there is nothing really eating up the chlorine?
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  20. Back To Top    #20
    Mod Squad pooldv's Avatar
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    Re: Can't get cc down

    Yes, that is a fair indication. I would stop adding MPS and elevate FC to 10 ppm and see what happens. I am not familiar with the R0867 reagent. Yes, it looks like it should stop the MPS interference. There is really no need to use MPS, it doesn't do anything for you that chlorine/bleach doesn't do better.

    Are you following this?
    How do I use Chlorine in my Spa (or pool)?

    Do you have CYA in the tub?
    TFP Moderator
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