We have an IGP, vinyl siding, @ 25000 gallons. We live in the northern US where winter means a solid freeze on the pool. For the past 7 years we have had a solid tarp as a pool cover (held down with water bags)which was great for keeping out leaves and awful to remove. After years of wrestling with it, and a few good sized tears, we decided to replace it with a mesh safety cover (the spring loaded kind that attaches to deck fasteners).
The good news was taking of the cover this spring was a piece of cake! Easy to remove, easy to clean and store. Also there were very few solids in the pool -- but holy algae batman! We had never seen the pool water so green.
We did our usual process of water balancing, super shock, and algaecide + 24/7 pool filter with daily filter cleanings, but we are still loosing significant chlorine ppm during the day. The odd thing is, we loose hardly any ppm over night. Here are the specifics:
At night we will add liquid chlorine. By morning, consistently numbers look like this:
CYA=less than 20
By night time, TA, PH, & (of course) CYA remain the same but FC drops to 6-8 ppm. During the day we have the solar cover off and it has been blessedly sunny during the day. The pool is mostly clear but not entirely.
SO here's the question. I know CYA is low but I hesitate to add any in the event that organics are still consuming the chlorine. If my issue is one of organics, than I am worried about adding CYA because then I will have to up my chlorine and I am already burning through my supplies. OR, is the fact that I retain chlorine PPM overnight and losing it during the day indicative of a CYA problem.
Any thoughts you have would be greatly appreciated!
25000, IGP, vinyl, chlorine.