Pool won't hold chlorine

[AndyMartha]

I'm having the similar problem others have mentioned, but don't see an answer that fits. I'm in Wisconsin. My ph and alkalinity are fine. No amonia, phosphates are fine. Am doing chlorine feeder, weekly shock, weekly algacide treatments. My water is clear. My pool won't hold chlorine. The only thing I can think of is that at one time early in the season, chlorine was too high. Dealer recommended a chlorine neutralizer. Could use of this keep chlorine from being stable? I used 3 pounds of shock last night. This morning my pool showed chlorine levels of 8 ppm. Tonight - none.

[Aquaclear-NZ]

the only part you have not mentioned is your CYA level
over dosing in neutrlaiser would not have helped the situation although bear in mind that sun will hammer out a good 80% of the free chlorine every hour with no stabiliser

[AndyMartha]

I've been having the product dealer do a test several times a week. After reading other posts on this site, I asked about the CYA level. They tell me the CYA level is the same as the stabilizer level. Mine is 100, their test says 30 to 100 is acceptable and that no treatment is necessary. So ph is 7.2, Total Alkalinity is 130, Calcium Hardness is 212, Stablizer is 100. But the pool is burning through chlorine. I added 3 pounds of shock at dusk on August 4. Less than 24 hours later I had 0 total chlorine and 0 free chlorine. I'm also going through a lot of ProTeam High Tech Tabs in my feeder. Yesterday we did a nitrate test - no nitrates. I put in a maintenance dose of algaecide. No sign of dead algae. Water is clear as a bell. I swam today, August 6 - and I must say I find the water irritating to my skin. The only recommendation the dealer has at this time is to blast the water with chlorine and keep it high for a couple of days to see if there is bacteria that needs to be killed off that is fighting the chlorine.

[rabneck]

Having your pool burn through chlorine this way can be very frustrating. I am pretty sure that 100 is a high cya level and a level that is too high can cause the chlorine not to hold. I try to stay in the 40 - 60 range. If your pool is 27000 gallons try draining a foot or so, maybe a foot and a half , and then refill and see if you get it to hold any better.

[chem geek]

Your chlorine is going away quickly because it is fighting algae growth. At a CYA level of 100 ppm (if it truly is 100 ppm -- some test kits max out at 100 so it could be higher), algae will grow faster than chlorine can kill it somewhere around 5 ppm FC or so and the recommendation at 100 ppm CYA is to maintain 7.5 ppm FC in a manually dosed pool. Lowering the CYA level will help you maintain a lower FC level. In the meantime, you need to shock the pool with a higher FC level to kill the existing algae (even if not visible). However, I'd dilute the water first to lower the CYA level to around 50 ppm (i.e. dilute by half). Then shock with 20 ppm FC maintained until the overnight FC drop is <= 1 ppm FC. Then maintain a minimum of 3.8 ppm FC.