CYA not registering after HTH added

[rhondave69]

Following recomendations here I have added 1.3lbs Walmart (95%) Stabilizer to my 5300 gal vinyl pool.
I used the panty hose method and hung it near return. It disolved very fast but from earlier posts this should not be the case? I still register 0 CYA level on AquaCheck test strips. Also dealer registers 0 as well.
I am also using Nature 2 system (my last year) and would like to maintain .5ppm Cl in midweek but it just won't hang around long with 0 CYA. Thanks

5300 gal.
FC 0
pH 7.6
TA 120

Dealer says he does not worry about CYA levels??????????

 

[The Mermaid Queen]

Your pool dealer does not know what he is talking about!

Is it possible that some of the CYA granules fell through the stockings and have not yet dissolved?

You will need to keep more than .5 FC in your pool, even with the N2 system, since the CYA limits the effectiveness of the Cl. You will also still have to add bleach daily (or at least every other day) in the evening to keep your FC levels up. While CYA helps keep the Cl in your pool, it is not a miracle worker! It will keep it for a day or so, but not a week!

 

[chem geek]

1.3 pounds of CYA in 5300 gallons should produce about 30 ppm CYA in the water. As Grace pointed out, it may not have fully dissolved, but I would have expected some sort of measurement on a CYA test -- but test strips may not be good for this sort of test. You should invest in a good test kit such as the one here which is essentially a better balanced (in terms of chemical quantities) version of the Taylor K-2006 test kit found here though it also has an OTO chlorine test as well for quick chlorine checks.

The Nature2 system is an expensive way to keep algae at bay and it will slowly kill bacteria, but chlorine disinfects much faster which is why it is required even when using Nature2. You should keep in mind that having even 4 ppm FC with 30 ppm CYA in the water is technically equivalent in disinfection and oxidizing power to having only 0.13 ppm FC with no CYA. If the reason you are using Nature2 is to keep chlorine levels low, then that is a false proposition. An outdoor pool exposed to sunlight and breezes and with CYA in it is extraordinarily safe with chlorine. All of the issues with asthma and respiratory problems with competitive swimmers and small children quoted on websites promoting alternative products for sanitation are ALL with indoor pools that do not use CYA, have poor air circulation, and no exposure to sunlight. Even at 2 ppm FC with no CYA in such pools, they have over 15 times as much disinfecting chlorine which results in 15 times the rate of production of disinfection by-products. The point is that YOUR pool, using CYA and 3-4 ppm FC, is far, far safer than the pools that have had problems with chlorine and no CYA.

As an alternative to Nature2, you might consider just using chlorine alone IF you are diligent about adding chlorine every day (or, if you get a pool cover, twice a week). If you feel you won't be able to maintain the chlorine level consistently, then you can use a weekly algaecide such as PolyQuat 60 that will prevent algae even if the chlorine drops to zero for a while, though clearly you shouldn't go into the water until chlorine is added and you wait several hours. Compare the price of PolyQuat 60 and the Nature2 to see what makes sense for you and also keep in mind that the copper from the Nature2 system can lead to green hair in blondes and to metal staining if the metal amount rises too high or the pH goes up too far.

 

[rhondave69]

Thanks.
After last nights shock (65% Sock It 12oz.) at 900pm I now test .5 ppm FC at 400pm next day with cloudy skies and pool temp of 77 deg. Is this normal? I will eventually ween off Nature2 but last year I used no Cl between weekly shocks and had no problem. But I still would like to add chlorine on Tue., and Thur. How much bleach and/or calcium hypochlorite should I add to raise FC?
Just received borate test strips and I have 30ppm from last year and will slow increase to 50ppm.

 

[The Mermaid Queen]

One of the benefits of the BBB 'system' is that most people hardly EVER need to shock. If you keep a consistant sanitizing level of FC in your pool, you will rarely get an algae bloom, and really only need to shock after a disaster, or a high bather load, or a baby in the pool, etc.
Really, you need to shock only if your CC level goes above 0 (some say .5) So that means more swimming time for the family, and less time waiting for the FC to drift down to 'normal' levels!!

Someone else can help you with the amounts to add... download BleachCalc if you have not already, which should be 'stickied' at the top of the Chem 101 forum!

 

[chem geek]

12 ounces of 65% Cal-Hypo in 5300 gallons should have raised the FC by 11 ppm. Such large usage is not normal and could indicate a nascent algae bloom. The next time you add chlorine at night, first measure it about a half hour later to make sure your chlorine test is measuring high chlorine levels properly. Then, measure it the next morning (early) to see if it is getting used up without sunlight (if it is, then you've got a nascent algae bloom or something that is consuming lots of chlorine in your pool). If the chlorine holds overnight but drops significantly during the day, then perhaps you really don't have CYA in your water (in which case, what the heck was in the sock over the return?).

It takes about 14 cups of 6% bleach to raise the FC in your 5300 gallon pool by 10 ppm.

 

[rhondave69]

I have brushed and vacuumed twice a day for a week.
No undisolved chemical or residuals remain. But still no CYA levels.
The pool is crystal clear. The Cl levels just do not last. Yes initial tests after evening application do show > 5ppm on test kits (I use 3 drop kits and 2 dip strip kits) but thats as far as far as they go for test levels.
Not sure what I have bought at Walmart bit can CYA go bad. I do have access to high level chemistry laboratory but how do you verify a container of HTH stabilizer?

 

[chem geek]

You can add a small amount of the HTH Stabilizer to a sample of your pool water and then measure the CYA with your test strip. If you don't measure any CYA, there was something wrong with the stabilizer or the test strip. I've never heard of CYA going bad. You can also repeat the experiment with tap water, but adding the CYA to it will make it very acidic which might affect the CYA test (usually, it would make the test more effective if a melamine turbidity test is used).

 

[Guest]

The ONLY test strip that I have ever seen that can remotely measure CYA with any accuracy are the LaMotte 6 way strips (and they are not all that great). Every other strip I have ever tried has been so far off (both high and low) that I consider their CYA tests utterly worthless! CYA in my pool is at 70 ppm by my own testing with Taylor reagents and with the LaMotte WaterLink Express lab colorimter and reagents we use at work. LaMotte 6 way reads 100 ppm, Pooltime (Chemtura, same company as Bioguard!) reads 0 ppm, and AquaChek Select 6 way reads 30-50 ppm! Take that for what it's worth! BTW, both the Aquachek and Pooltime strips use the same chemistry for their CYA test but the LaMotte uses a different one (based on the color comparator). The first two strips have a color change that goes from orange (O ppm CYA) to brick red while the LaMotte strips have a CYA test that goes from yellow to green for 0 to 250 ppm CYA.