I am a new member and must start with saying thank you for providing such a great site with excellent information. Now on to my question:
I have a 40,000 gallon in ground plaster pool in Southern California with a DE filter on it. I bought this house and the pool was already in place so I have no idea how long the water has been in it. The CYA level is very high - 250 according to the tests done at the local pool supply store. According to the charts posted here I calculate that I need to keep a FC level of 17 min, 30 target, and 100 shock. Is it safe to swim in the pool with FC levels up to 30? The local pool store folks don't seem to acknowledge a relationshop between FC and CYA so they say don't swim if the FC is over 5. Also how do I find a test kit that will register FC levels this high? I have been doing a dilution of the sample with distilled water to get readings over the 5 that my test kit tops out at. I do this by mixing pool water with distilled water in measured amount then running the test and then the math. If I have 25% pool water in the test then I take the ppm result times 4 to get my FC level.
Wow, I guess I have a lot of questions but I will stop for now and again i REALLY APPRECIATE ANY HELP YOU CAN PROVIDE.
Current pool chemistry:
FAC - 6
CH - 230
CYA - 250
TA - 80
pH - 7.5
TDS - 1700
Phosphates - 300
I have been recently using liquid chlorine and muratic acid but was previously using tabs in a floater (this forum told me about those increasing CYA so I switched)