No Chlorine Stability

[Roger B]

problem is same or similar to what you are talking about, no free chlorine.
All of items, CYA, pH, etc are ok (proper levels). Water is perfectly clear.
As someone mentioned, have spent big bucks and seem to be moving backwards. Many attempts at normal shock with no results. Thursday pool store told me to super shock with 5 lbs of granulated chlorine (28,000 gallon pool).....no improvement. On Saturday, he told me to do 10 lbs, putting 7 in the pool and divide 3 lbs between the 2 skimmers. He said I may have fungus in the lines. This morning, still reading no free chlorine. Again water is or looks excellent, as far as being clean and clear......I may have stumped the stores, 2 good ones......any help wold be greatly appreciated.

Roger in Richmond, VA

[Buggsw]

Roger, it's best to start your own thread, so you don't lose track and so it is less likely people will get confused as to the recommendations and answers.

That being said, I will try to help you here.

Who is testing your water? You or the pool store? What type of test are you using? sticks or drops? are the drops OTO or FAS/DPD?

Sticks are the most unreliable tests to use unless you know your water is in balance and are just using them for a quick check for minor adjustments. Also some sticks are just plain lousy. If your chlorine level is high, they will bleach out and show as if no chlorine.

OTO is a little better, but only tests to 5 unless you use distilled water to dilute and factor that in by multplying the result.

FAS/DPD tests will read accurately up to 20 and will still register higher than 20, though not quite as accurate.

Also, if they are using a machine - those can be terribly wrong, too.

So, I would recommend testing with a FAS/DPD test kit.

If you are still not getting a reading, then I would have your water tested for phosphates. Phosphates are food for algae. If you have a high phosphate level, you may not be able to keep your chlorine high enough to snuff out all the algae. In short, you may be keeping an algae buffet.

[RogerB]

thanks for your reply. We use sticks at home and normally take it to a Pool Store about weekly. There are not many good pool places in Richmond, but 2 stand out. The one we work with the most, has been very good in the past 5-10 years. They use the drops, however I dont know the type. Normally the sticks will tell us the range, but we do rely mostly on them. I looked at the results sheet tested yesterday, no phosphates, so I dont know where we stand on that. Tell me what to do for my on thread and I will get it going. We went ahead and shocked again today, 10 lbs ......I may be wasting the chlorine......Back shortly

Roger (thanks Pool Pro)

[Buggsw]

I wish you would have posted your CYA, if it's over 50 you will need to add more chlorine than I am recommending.

Use regular liquid chlorine - can be regular strength Chlorox which is 6% or Pool Store chlorine which is 10% or 12.5%

Of 6% Chlorox - you need to use 7 gallons - buy extra because you will need to add it day and night to keep your TC up to 15.

If you use 12.5% - you will need 3.5 gallons to bring it up to 15.

The goal is to bring it up to 15 and try to keep it there. If it drops overnight, you need to add more chlorine during the day to bring it back up. When your chlorine reading stays at 15 overnight you can then let it fall back to normal.

Get yourself a FAS/DPD test kit. If you use an OTO kit, you will need distilled water to dilute your sample either 1:1 or 2:1. If you do this, you will need to multiply your reading by 2 or by 3, whatever your dilution. It's not totally accurate - but can be used in a pinch.

Keep your pump running until your water clears. What I suspect you have been doing is shocking, but not able to kill all the algae and your chlorine is losing effect quicker than all the algae can be killed. If your CYA is over 50 you need to use even more chlorine and shock to about 25.

Keep your pH at 7.2 - 7.4 during this process.

[pool guy 78741]

If you cyruanic acid (stabalizer) is too high (result of cal hypo tabs) or too low (result of liquid) your chlorine levels will not read correctly. A good test kit will have a test for it. If it is too high you will have to drain your pool. Too low is easy to fix just add some to the pool. Ideal levels are around 50ppm.

[Gullible]

Pool guy,
Please do not give advice if you do not know anything. Wrong on both accounts. You making fool of yourself.

[chem geek]

If you cyruanic acid (stabalizer) is too high (result of cal hypo tabs) or too low (result of liquid) your chlorine levels will not read correctly. A good test kit will have a test for it. If it is too high you will have to drain your pool. Too low is easy to fix just add some to the pool. Ideal levels are around 50ppm.

Cal-Hypo tabs do not increase the Cyanuric Acid (CYA) level. Instead, they increase the Calcium Hardness (CH) level. It is Trichlor and Dichlor that increase CYA. Using chlorinating liquid or bleach does not lower the CYA level -- only water dilution will do that such as from backwashing, splash-out/carry-out, intentional drain/refill, etc. Evaporation and refill will not lower CYA nor CH and can increase CH and TA from that which is in fill water. The following are chemical rules of fact that are independent of product concentration or of pool size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases CH by at least 7 ppm.