Second summer as a pool owner. We found out about the BBB method about halfway thru last summer and by that point the CYA was already in the 90s. Using the pool calculator and a complete test kit we had the pool sparkling all summer...even with the high chlorine demand.
Drained off a good bit of water for winter closing so I was hopeful that we could have a lower CYA this summer...and not have to keep the chlorine so high. Pool opened beautifully - balanced from day one. Never even had to shock it - passed overnight chlorine loss test from the start.
Current readings as of ten minutes ago
Combined chlorine 0
Free chlorine 3.5 --------this is what I need help with! I can't keep the chlorine up in a decent range. Last night the chlorine was at 3 so I added a 128 oz bottle of 10% and a 128 oz bottle of 8.25% bleach....thinking that would bump it up to the top of the range and keep it in range for a couple days. I fell asleep before I could do a reading for an overnight test after adding the bleach...but as of tonight (about 24 hr after adding the bleach) I'm back to 3.5.
I'm going to add bleach tonight and do an overnight test again just to make sure something isnt brewing. If it is then I know I need to go through the shock process.
The thing is that the pool gets a solid 8-10 hours of direct sunlight everyday. Could it be losing that much chlorine just from the sun? If I pass the OCLT should I increase the CYA level? If so, what would be a good level to raise it to?
Last year we got to where we added one or two bottles of bleach about every third day....that kept things at the right levels. I'm currently having to add one or two bottles EVERY day. I'm not a fan of that!!
On the plus side the pool is gorgeous - so sparkly and clear. Not too shabby for a 15 year old pool!!
Oh I almost forgot - it's a 20x40 Grecian shape pool....best guess is 32,000-33,000 gallons. Vinyl liner. Haywood pump. Use a 380 Polaris to clean.
Thanks for any advice!!M