CYA levels vs chlorine utilization

[ErniesPool]

I seem to be using a lot of chlorine. The pool has been shocked, stabilized, and my readings are:

CYA - 50
pH - 7.6
CA - 270
Tot AL - 70
pool volume - 18,500 gal (in ground plaster)
Taylor K-2006 test kit

Every evening I run the chlorine to 5 ppm. By the next afternoon I am down to 2.5 ppm. I am using about 70 oz of 8.25% bleach every day. That will run me about $50/month, quite a bit more $$ than when I was using pool store trichlor or dichlor pucks (if you ignore the cost of changing out the water every so often).

If I increase the CYA to, say, 70, theory says I will use less chlorine but I will have to go to 5 ppm chlorine to have the same oxidation effect. So, here is my question. Will I really save on chlorine? I'm losing about 50% per day now. What percent will I lose by going to a CYA level of 70? That will allow me to calculate what any savings might be.

 

[JasonLion]

Yes, the amount of chlorine you will need to add will go down if you increase CYA. The exact amount it will go down by is difficult to predict. Try CYA around 60 first and see what happens.

 

[Bama Rambler]

You're losing about 2.5 ppm FC per day. That's not bad at all.

Raising your CYA to about 70 might get you to about a 2 ppm per day loss, but that's about the best you can hope for.

 

[Smykowski]

You may have something growing in the pool because you're letting the FC get too low. With CYA at 50, your absolute min hard floor for FC is 4. If you let it get below that you're asking for trouble. You should dose to 7 or 8 and replenish when it gets to 4 or 5. May want to take the chlorine up a bit and run an OCLT to make sure.

 

[ErniesPool]

OCLT did not change overnight, so nothing is growing in the pool. That means my loss is due to UV. Guess I am just looking at about $50/month in bleach costs for the summer at least.

 

[Bama Rambler]

You might try looking around for stronger bleach. Sometimes the pool stores have it cheaper that 8.25% bleach costs.