I'm relatively new here, and I've learned so much from this site! I have an unintentionally green cement pond that I'd like to reclaim as a swimming pool. It was built in 2000 and has never been drained, so it has some wise old hardened water in it:
July 13, 8:15 pm
The Alkalinity and pH are too high, especially since I have all that calcium in the water. I added acid to bring both of them down. I also did a slight drain and water re-add. The source water is hard, so I'm going to have to mostly manage this through pH control, but I can make slow gains to get it beneath 1000 eventually. Right now, I'm concentrating on pH and chlorine. Let me know if I'm off-track on this.
I'm really relieved about the CYA. I've been paying no attention to it, and I've been using di-chlor and tri-chlor in the pool. So, the only thing I can figure is that something ate the CYA over the winter, and the tablets and haphazard shocking I've done to-date have killed that off so that the CYA in the tablets has re-taken some hold. That's my current theory, anyway, other thoughts welcomed! Also, the reading was somewhere between 40 and 50, and with the visibly murky, green water in the vial causing a little bit of a visibility issue by itself, the test is probably reading a little high.
Assuming CYA of 50, the PoolCalculator indicated a shock level of 16. I added 3 121 oz jugs plain old liquid bleach (8.25%) to reach it. I figure the first 2 days will see enough low FC tests that I can reliably re-check pH. Of course, once the chlorine starts to hold, I won't be able to do that any more.
July 13, 9:15 pm
Added 3 121 oz. jugs of 8.25% bleach.
July 13, 10:15 pm
July 13, 11:15 pm
Added bleach and called it a night.
July 14, 9:30 am (after buying a LOT more bleach)
CYA: somewhere between 40 and 50, not too accurate right now with the green water
Added bleach. I think I'm ok with this pH level until the algae is gone--let me know if I should give it a nudge down a little more.
July 14, 10:30 am