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Thread: How to get rid of white dust and scaling and too high pH?

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    How to get rid of white dust and scaling and too high pH?

    Hello:
    We run two pools on Hypochlorite in the Philippines. Water temp. constantly around 30Ā° Celsius. The chlorine disappears nearly quicker than it can be replenished, white dust everywhere even now that we donĀ“t throw the granulate directly in the water anymore but in a sock placed in the water or skimmer, scale is forming and the pH is always around 7.8, nearly impossible to lower it with dry acid.
    The pool dealer told us to use Guardex conditioner, Quote: "This chemical, when added to your pool water with the Niclon Chlorine, would be similar to the effect an organic chlorine would produce". The question is now: 1.: To have the Hypochlorite last longer I neeed CYA. Will it then be really the same as stabilized Chlorine? But to get rid of the scaling I better donĀ“t use Hypochlorite, right? If I use stabilized chlorine which should dissolve completely there is really no white dust and scaling anymore? But then the CYA will get too high over time. If I use pucks the same problems, I would like to know how long a 3" puck lasts in the skimmer on lets say 10 hrs pump run time?
    How about using an SWG in CYA stabilized water, no fine dust and scaling and rising pH anymore?
    Ideal seems to be liquid chlorine together with 25 ppm CYA. Why there is no 100% liquid chlorine available?
    The same with acid, why there is no 100% acid? Is the dry acid more enonomical than bleach? How much 100% acid makes 5 Kg of dry acid?

    Alum potass filter aid which seems to be readily available here since it is used as a anti-transpirant: How introduce it in the water, dissolve first or in the skimmer, how much to use per 5000 Gals?

    Hope for a qualified answer out here.
    Hayward Pump SP2805X7 Hayward Sandfilter S210T used by switching a manual threewayvalve for either a IG overflowpool with 3700 Gal. or a second IG skimmerpool with 5550 Gal., both tiled with white cement grout and white cement/beachsandrim, the upper pool with sculptured white cement/beachsandwaterfall. Test results: All OK

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    JasonLion's Avatar
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    Re: How to get rid of white dust and scaling and too high pH?

    It would be very helpful if you could post a full set of water test results and a list of what chemicals you are using. It is difficult to speculate about what might be happening without that.

    When you say hypochlorite, do you mean sodium hypochlorite or calcium hypochlorite?

    Chlorine is very volatile. The higher the percentage the more rapidly it breaks down. 100% liquid chlorine, if you could make it, would break down almost instantly and become a lower percentage. 18% liquid chlorine, the highest percentage you normally see, has a self life of under a month at temperatures lower than what you describe. Higher temperatures mean an even shorter shelf life.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: How to get rid of white dust and scaling and too high pH?

    While waiting for your test results which would help explain why you see white dust and scale and higher pH that seems stuck, let me try and answer some of your questions. I put your questions in italics and my answers are below.
    Quote Originally Posted by sunrisepalaisboracay
    Hello:
    We run two pools on Hypochlorite in the Philippines. Water temp. constantly around 30Ā° Celsius. The chlorine disappears nearly quicker than it can be replenished, white dust everywhere even now that we donĀ“t throw the granulate directly in the water anymore but in a sock placed in the water or skimmer, scale is forming and the pH is always around 7.8, nearly impossible to lower it with dry acid.


    There are many reasons that chlorine demand could be too high which is why we need your pool's water chemistry numbers to know. One possibility is that there is little or no Cyanuric Acid (CYA), aka stabilizer or conditioner, in the water. If the pool is exposed to direct sunlight, then without CYA in the water half of the chlorine can break down from the UV in sunlight every 35 minutes. Another possibility is that the CYA level is high and the FC too low relative to the CYA level. In this case, the chlorine demand could be from nascent algae growth, even before the algae has become visible (i.e. water dull then cloudy then green).

    The pool dealer told us to use Guardex conditioner, Quote: "This chemical, when added to your pool water with the Niclon Chlorine, would be similar to the effect an organic chlorine would produce".

    The word "conditioner" most likely refers to Cyanuric Acid (CYA). So your dealer is assuming that the problem in your pool is that you never added CYA and have never used stabilized chlorine. Though this may be true, testing your pool water chemistry, including CYA level, will let us be more certain about that.

    The question is now: 1.: To have the Hypochlorite last longer I neeed CYA. Will it then be really the same as stabilized Chlorine?

    IF you don't have any CYA in your water AND your water is exposed to direct sunlight, then you definitely need to add CYA to the water in order to prevent sunlight from breaking down chlorine quickly. Even if your pool wasn't exposed to direct sunlight, it's still a good idea to have some CYA in the water to prevent the "active" chlorine from being too strong. Yes, having CYA added to the water along with unstabilized chlorine is IDENTICAL to using stabilized chlorine in the water, ignoring the effect on pH from using different chlorine sources (e.g. Trichlor pucks are very acidic).

    But to get rid of the scaling I better donĀ“t use Hypochlorite, right? If I use stabilized chlorine which should dissolve completely there is really no white dust and scaling anymore? But then the CYA will get too high over time. If I use pucks the same problems, I would like to know how long a 3" puck lasts in the skimmer on lets say 10 hrs pump run time?

    Using hypochlorite sources of chlorine do not cause scaling. Scaling is caused by incorrect water balance and this is a combination of pH, Total Alkalinity (TA), Calcium Hardness (CH) and to a lesser extent Cyanuric Acid (CYA) and temperature. This is, again, why we want to know your water chemistry parameters.

    For example, if your TA level was too high, then that would tend to make the pH of the pool rise so that combination plus a possibly high CH could lead to scaling. One solution to this is to lower the TA level since that helps solve the scaling problem directly and also slows down the rate of pH rise. Again, we need to know your water chemistry parameters in order to give you the proper advice.

    At this point, if you were to use stabilized chlorine, it would not solve your scaling problem unless the Trichlor puck usage was acidic enough to bring your pH down. Since you are having trouble bringing it down with dry acid, the Trichlor pucks probably wouldn't be enough to help either. The problem with the pH staying high is most likely due to the TA being too high, but again...well you get the idea.

    How about using an SWG in CYA stabilized water, no fine dust and scaling and rising pH anymore?

    An SWG pool does typically have CYA in the water, usually a lot of it to minimize chlorine loss from sunlight so one can keep the SWG turn on time as short as possible. However, SWG pools typically demonstrate a rise in pH, though that can be minimized through techniques described in this post in the Pool School. However, it should not at all be necessary to go to an SWG to solve your problems with your pool. The SWG would mostly just provide more convenience in not having to add chlorine regularly -- it is not necessary to keep a pool free from algae nor to prevent scaling.

    Ideal seems to be liquid chlorine together with 25 ppm CYA. Why there is no 100% liquid chlorine available?

    As Jason pointed out, the chemistry prevents their being a safe form of 100% chlorine. The 100% form of chlorine is chlorine gas and would be unsafe for residential customers to use. It is sometimes used in some commercial environments or with a few pool services, but it is less common. There is absolutely nothing wrong with using chlorinating liquid (or bleach) in a pool that already has CYA in it. In fact, it's what most people on this forum do (unless they have SWG pools) and have minimal problems with their pools. As for the CYA level that is best to use, that depends on your situation, but typically it's 30-50 ppm unless you've got a lot of strong sun in which case a higher CYA level (but not more than 80 ppm) is sometimes used. This chart in the Pool School shows the FC level needed at various CYA levels.

    The same with acid, why there is no 100% acid? Is the dry acid more enonomical than bleach? How much 100% acid makes 5 Kg of dry acid?

    The dry acid is nearly 100% pure substance though there is no such thing as 100% pure acid since the "acid" portion (which is positively charged) needs to be attached to something (negatively charged). Dry acid is usually 93.2% sodium bisulfate. However, since this builds up sulfates in the water, we sometimes recommend using Muriatic Acid which is usually 31.45% hydrochloric acid (full-strength). This is very strong and often fumes and is irritating, so one can get half-strength that fumes less. Dry acid and full-strength Muriatic Acid are roughly the same acid strength by volume.

    Acid and bleach are two completely different things. Bleach is the same as chlorinating liquid except it's not as concentrated so it is a source of chlorine.

    I don't understand your question regarding 100% acid equivalent of 5 Kg of dry acid. 5 Kg of dry acid is equivalent to 3.9 liters of full-strength Muriatic Acid and is a LOT of acid. You would never add that much to a pool unless the pool were at least 100,000 liters (26,400 gallons) and you wanted the pH to drop significantly (say, for the procedure that lowers the TA).

    Alum potass filter aid which seems to be readily available here since it is used as a anti-transpirant: How introduce it in the water, dissolve first or in the skimmer, how much to use per 5000 Gals?

    Alum is usually a flocculant that consolidates particles and has them settle to the bottom of the pool where you need to vacuum-to-waste to remove them. It sounds like the particular product you refer to is more like a clarifier that consolidates particles to have them get trapped more readily in a filter. These products are not usually necessary if you are properly maintaining your pool. Please tell us more about your pool (such as pool size, filter type, etc.).

    Hope for a qualified answer out here.

    As Jason said, we can give you much better advice if you follow the guidelines in this post and give us more information about your pool and equipment characteristics and its water chemistry values.
    Hope that helps. Please read this Pool School post about the information we need in order to help.

    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: How to get rid of white dust and scaling and too high pH?

    Thanks to both of you Jason and Richard, that explains already a lot. All the available info about our pools I listed below in my signature. I have only a Hayward IMG Testkit that shows free chlorine reading mostly in the 0,6 range, combined chlorine reading nearly the same. No wonder since we donĀ“t use CYA because the pool dealer did not tell us about it, I just learned thatĀ“s is neccessary right here. pH stays at 7,8 and seems not moveable even with around half pound of dry acid at once. Is it possible that the test liquids are too old after 3 years? How to measure the other values if I canĀ“t have your tester shipped here, the local dealer also has 4in1 testers, another dealer has Taylor complete test kit at nearly 100 US $. Is that your TF kit Jason?
    We use Calcium Hypochlorite. One pool gets sun around 10 hours, the other only 5 hrs. And yes, thatĀ“s exactly what we expirience, very quick breakdown of the chlorine because of no CYA. So we have to get that immediately. The dealer should have sold us that right in the beginning. Maybe that would already solve the white dust and scaling problem since I donĀ“t have to use the 100 to 150 grams/day of chlorine to each pool anymore but much less, right?
    You say hypochlorite does not cause scaling, the guardex pool maintenance brochure says anorganic calcium hypo does and recommends it` s stabilized organic chlorine, thatĀ“s why I thought I have to buy that. I can get this here:

    3. Nikkon Calcium Hypochlorite 70% granular 50 Kgs/drum
    Origin Japan 1 drum P 5000 = about 100 US $
    4.
    Origin Bestchlor 60% ( SDIC ) granular, 50kgs/ drum
    Japan 1 drum P 10,500 P 10,500.00= about 210 US $
    5.
    Origin Bestchlor 90% (TICA) granular, 50 kgs/ drum
    Japan 1 drum P 10,500 P 10,500.00
    6.
    Origin Bestchlor 90% (TICA) tablet , 50 kgs/ drum
    Japan 1 drum P 11,500 P 11,500.00

    Until now I donĀ“t know what TICA and SDIC means, have to ask them or do you know?

    Since you say pucks are very acidic maybe itĀ“s just right so they supply some of the neded acid for our situation? The tap water comes from a deep well in or next to a river on the mainland, maybe itĀ“s quite hard.

    Clorox bleach 6% costs about 3 US $ per Gallon here.

    Now the big question is what is more economical? That is what I can get here, which would you use? How long lasts a puck in a skimmer? I donĀ“t mind throwing the granules in, either. To me only 6% useable chlorine in a Gallon sounds little, but you say itĀ“s used by most of the forum members, so would I if itĀ“s economical of course.

    The pools are in operation for 6 months, after that are being used as a water tank only since we are out of the country and the caretaker canĀ“t maintain the water quality for a pool. After we return the water is drained and refilled with tap water for pool use again. So that means CYA levels canĀ“t get out of sight in only 6 months of water usage.

    As for the acid: Sorry I mixed it up with bleach, I meant muriatric acid. I can get this here from the pool dealer:
    7.
    Origin Muriatic acid 32% Apollo
    philippines 1 cby P 700 P 700.00 = 14 US $ However, I donĀ“t know which amount "1 cby" is, have to ask, but as you write it does not build up sulfates so I will use this. Otherwise muriatric acid 12% from the supermarket at 5 $ per Gallon. Depends on what a cby is what is cheaper.

    About the potassium alum I meant flocking powder so the sand filter can trap smaller particles. The dealer told me that is the potassium doing. So I need clarifier if at all.

    Hope for more answers about which form of chlorine to use, will skip the SWG for now. Great to have you experts here, our pool dealer is of not much help, does not know too much about what he is selling, we are in a 4th world country here.....
    Hayward Pump SP2805X7 Hayward Sandfilter S210T used by switching a manual threewayvalve for either a IG overflowpool with 3700 Gal. or a second IG skimmerpool with 5550 Gal., both tiled with white cement grout and white cement/beachsandrim, the upper pool with sculptured white cement/beachsandwaterfall. Test results: All OK

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    JasonLion's Avatar
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    Re: How to get rid of white dust and scaling and too high pH?

    Calcium Hypochlorite - we tend to call this cal-hypo. It adds chlorine and calcium to the water.

    Bestchlor - this is probably what we call trichlor, though it might be dichlor. I can't be sure which one it is, or if the different percentages are different ones. Either way, it adds chlorine and CYA, and also lowers the PH. This is probably why they didn't mention CYA, if you use this product you are already adding it.

    "1 cby" - presumably a carboy, though that doesn't tell you much. In the US a carboy is most commonly 2 1/2 gallons, but the term is also used for containers of several other sizes.

    How long a puck lasts in the skimmer is an interesting question, but has nothing to do with how economical pucks are. Each puck adds a fixed amount of chlorine. Pucks come in different sizes, so I can't tell you exactly how much unless you weight one. The rate at which pucks dissolve depends on how warm the water is and how much water is flowing over them, anywhere from one day to a week.

    TF Test Kits is a separate company, despite the similar names. TF Test Kits is run by duraleigh, a member here. He is able to ship to almost anywhere except Canada.

    I suggest you get a TF100 from TF Test Kits if you can. TF Test Kits uses Taylor chemistry and provides larger quantities of most of the reagents in their kit, so it usually ends up being a better deal in the long run. Taylor makes a number of different test kits. If you are getting a Taylor test kit, the one you really want is the K-2006. That is the only Taylor kit that includes the FAS-DPD chlorine test, which can be very important in some situations.

    White dust tends to be calcium dust, though there are other less likely possibilities. Calcium dust and calcium scaling are both caused by a combination of relatively high PH, high TA, and high CH levels. From your description, I suspect that you have a very very high TA level and also a fairly high CH level.

    Getting through water test results should be a high priority. The exact treatment for your problem depends on knowing exactly what is wrong. Water test results can tell us that. Otherwise we need to guess a lot, which frequently leads to errors and wasted chemicals. Depending on how long it takes to get a really good test kit, it might be worth getting the less expensive four way test kit, just for now so we can get some idea of what the levels are while the better test kit is on order.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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