Green water in pool

[Dudek]

membership updated to "general" (moderated) status.

Basically, I trust you about as much as you trust me.

Thanks. “Trust but verify”. The water has just cleared up and I can read a dime heads or tails in the deep end. So far free chlorine and total chlorine have been good in the morning and zero by the end of the day. I don’t have a CYA test so I took a water sample to a pool store and they said my CYA was 30 and all other levels matched the readings I got which were all good, Ph on the high side 7.8 – 8 which again exactly matched the readings I got with my test strips. This recently elevated Ph elevated could be because of rains we’ve recently had (it was 7.2 – 7.6 up until before the recent rain) and accumulative effect of the recent daily super chlorination (shocking) in the evenings.

I’m assuming the daily chlorine consumption is due to the heavy algae problem that just got cleared up and low CYA. Pool store recommended a 4 pound tub of CYA and I added ~ 3 lbs. The instructions said not to backwash for 72 hours so I am assuming that it takes roughly 72 hours for this particular formulation to fully dissolve.

Last year I had clear water and maintained free chlorine and total chlorine at a consistent 1-3 using 3 chlortabs in the floater and shocking the pool with 2 lbs of HTH (60% available chlorine) every 7-10 days, which was when then chlorine levels would drop to zero. The chlortabs would last about a week or so before needing to be added again depending on heat, swimmers, etc. I did not add CYA last year but we didn’t have an algae problem either. The worst it got was a slight milky color once or twice that cleared up overnight by shocking the pool and running the filter constantly up from the normal 12 hours per day on timer – 2 hours on, 2 hours off. I tested all last year with test strips.

I will likely discover this on my own but will the need to super chlorinate every evening to bring the free chlorine and total chlorine back up from zero to the ideal 1-3 range taper off? I’m hoping the increased CYA will slow down the chlorine consumption and bring it back to last year’s consumption rate.

I wasn’t able to test this evening and I did not super chlorinate. I’ll be using my last test strip tomorrow morning and in part the pool store visit was also to verify that my test strip readings were actually on the mark according to their water testing equipment. I just had my first day of clear water this season so I’m happy about that.

[PoolDoc]

We push the K2006 very, very hard for several reasons:

1. Pool store test are usually rather inaccurate, and strip based tests for CYA are horribly inaccurate. You cannot run your pool successfully over the long term without knowing what your CYA levels are. Remember, pool stores make MORE money, if your pool stays screwed up, so they have ZERO incentive to use more accurate, but more expensive test methods!

2. As CYA levels rise, you need chlorine levels to rise in compensation. (The Best Guess page, linked in my signature explains). The ONLY way to do this is use OTO (yellow drops) at ranges NOT shown on the test kit, OR to use the DPD-FAS testing Taylor developed, which is found in the K2006. Pool stores do NOT sell kits with DPD-FAS test methods.

So . . . get a K2006 and use it. Trying to answer the questions you have posted above, without the chlorine and CYA info, is a bit of a waste of time on both our parts. To some degree, what you've posted is just an example of what we've always taught: if you can get your water half-way right and KEEP it there, a month of normal care is much, much easier than even a single brief algae episode.