Thoughts as to What is Consuming Chlorine

[yossarian]

I passed the OCLT last week and thought I was good to go, so I let the FC drift back down to normal levels over the course of the weekend. On Monday night, I tested a FC of 7. The next morning I was at 5.5 FC, with CC of .5, so I figured it was time to shock again.

Here are what my test results were over the course of the next few days:

CYA<30 ( I assume 30 for the tests)

Monday -- 8 FC, 0 CC (9 pm)

Tuesday -- 6.5 FC, .5 CC (5:30 am)
14 FC, 0 CC (9 am, following shock)
12 FC, 0 CC (8:30 pm)
14.5 FC, 0 CC (9:30 pm, following shock)

Wednesday -- 13 FC, .5 CC (5:30 am)
11 FC, .5 CC (8:30 pm, no chlorine added in the morning as I was still at shock level)
13.5 FC, 0 CC (9:30 pm, following shock)

Thursday -- 11.5 FC, .5 CC (5:30 am)

I am losing between 1.5 and 2 FC overnight. Yet, I was not losing any more than that during the day this week (It was intermittently cloudy and rainy those days, and I have had my solar cover on all week; I even had a dead mole and frog in my skimmers one of those evenings and still only lost 2 FC during the day). I am finding CC of .5 or less. I brush the pool and get a little bit of dust, but not any other debris. The pool looks clear, the filters are clean.

I thought that maybe the rain had been a cause of the FC loss on Monday and Tuesday evenings. But yesterday evening was clear outside. And I did extra brushing last night.

 

[zea3]

For one you need to bump up the CYA a little higher. It is less than 30 now and if you have a lot of splashout it will drop fairly quickly. Raise it up to about 40 ppm and you won't have to worry about it dropping too low with splash out and rain dilution.

As for the overnight FC loss, did you scrub behind any ladders and light fixtures? Anything in the pool that can be pulled out and scrubbed may be harboring a little live algae. Light niches and ladders are famous for this.

 

[mrswhitsie]

Dead Mole! Gross! I thought crabs that blew up in my cleaner were bad! I am wondering what folks respond to this as my Chlorine diminishes super fast too and my CYA is along the same levels. Thanks for posting.

 

[yossarian]

For one you need to bump up the CYA a little higher. It is less than 30 now and if you have a lot of splashout it will drop fairly quickly. Raise it up to about 40 ppm and you won't have to worry about it dropping too low with splash out and rain dilution.

As for the overnight FC loss, did you scrub behind any ladders and light fixtures? Anything in the pool that can be pulled out and scrubbed may be harboring a little live algae. Light niches and ladders are famous for this.

I am going to raise the CYA. I was hoping to do it with tri-chlor, but that makes monitoring FC levels difficult (for purposes of the OCLT).

There are no ladders in the pool, although there are 2 light fixtures. But they are not at all easily removed. I shudder to think at what it would take to remove them.

I suppose there could have been some algae on my solar cover, no?

 

[yossarian]

Dead Mole! Gross! I thought crabs that blew up in my cleaner were bad! I am wondering what folks respond to this as my Chlorine diminishes super fast too and my CYA is along the same levels. Thanks for posting.

I will take a dead mole over a blown up crab all the time. The mole was in the skimmer and I didn't have to touch it or anything. There was no real clean up. Where we are, it is pretty much impossible to avoid moles, mice, etc. I bet we get at least one furry critter a week in June and in September. Twice last year I had to get big mice out of the bottom of the pool. The only way they could have gone to the bottom was if they were dropped, as in by a hawk or eagle. That was pretty unpleasant.

 

[zea3]

Algae on the solar cove is a possibility.

 

[yossarian]

Algae on the solar cove is a possibility.

I am going with that. I uncovered the pool today and did a serious brushing. I disturbed a lot of sediment, which really clouded up a previously clear deep end. I suspect that most, if not all of it, was already dead since I have been consistently over shock level. But, as I have learned, clearing out the dead algae is critical to passing the OCLT.