Using Bleach in the Pool

[aylad]

The idea behind testing to see if you have a chlorine demand is that chlorine is consumed by two things: sunlight and pool goo. You can't really judge by looking at a 24 hour chlorine consumption whether you still have algae, because you don't know how much of the chlorine was consumed by the sun and how much by the goo. That's why you need to test at sundown after the sun is off the pool and again in the morning before the sun hits the pool if you're trying to establish whether your algae is all dead. You are always going to lose some chlorine during the day, due to the sun.

With a CYA at 100, you still need to keep your chlorine at a minimum of 8 ppm, otherwise you're inviting algae to start. You'll need to look at your results taken at night and in the morning to determine whether you still have an algae problem or just dead algae that needs to be filtered out.

If your chlorine is at 2, you need to add more bleach to get up to at least 8 ppm--but if you determine that you still have overnight chlorine consumption, then you need to shock it up to 25 ppm.

[Watermom]

Maybe Janet has already mentioned this to you in your thread and I just missed it when I scanned through it but you need to buy a good kit. Especially if your CYA is over 100 like you think it is, you'll have to run higher chlorine levels than the kits you'll be able to buy locally will be able to test. You need to buy the Taylor K-2006 or 2006C kit which you can find in Janet's (Aylad) signature block in post #2 above. It can register chlorine levels up to around 50ppm I think as opposed to around 5 like most kits.

[Schooled by Pool]

Tested tonight (had to go away for the w/e). It was 2 for chlorine. 7.4 for ph and the CYA was over a hundred. I had to use an old tube for the CYA test and the reading #s only went up to 100. I am guessing it was over 120 based on the spacing of the lines, but it is a guess. I will test again in the morning.

I have 9 gallons of 6% bleach waiting to go in the pool if necessary and can get more. The pool is slowly, very slowly, clearing (1.5 weeks after initial shock treatments), but is still cloudy, especially in deep end. No new algae has popped up. I can still see dead algae on the bottom.

[Schooled by Pool]

@ aylad, the test this morning showed chlorine between 1 & 2. LAst night was 2, but the lighting was different, in the room, so maybe that affected the change in the reading? Ph remains at 7.4 and the CYA remains above 100, at approx 120.

Water in the pool remains cloudy.

@Watermon, I am going to buy at Taylor Kit. I tried to find something locally when I came back into town, as a stopgap, but was shut out.

[Schooled by Pool]

OK. While waiting for my new test kit to arrive (Taylor 2006C) I tested the pool Sunday night, Monday morning and Monday night, Tuesday Morning and Tuesday night. All tests were similar, Chlorine near 2 (+/- .5) , ph at or near 7.4, CYA at 100 - 120 (guess because the tube only goes to 100). The pool is still slowly clearing, but cloudy (for past 2 weeks). I went ahead and put 8.5 gallons of 6% bleach last night, after the last test, tested again this morning, all levels are the same, except the chlorine, which is not measurable beyond 3 on my current drop kit. Clearly, the Cholrine has spiked, as intended. I calculated that I should have added over 20 ppm to the chlorine count, which would leave me short of the suggested 25 (I had no more bleach). If there was any more living algae in there, hopefully it will still be enough. Thats all I have for now.

[Schooled by Pool]

OK, my Taylor kit arrived. I tested pool last night. It was 6.2 FC, 7.4 ph, 120 ppm TA, 450 hardness, CYA off the charts...well above 100, probably around 150, but that is a guess based on how far below the 100 marker that the warer level was. I added 182 ounces of 6% bleach. This morning the FC was 9, CC was 4, the rest of the readings were the same as last night. Forgot to write down the CC last night, so I have no comparison.

Water remains cloudy and slightly green. Still unable to close the pool and cover it. This has been going on for a month now. Thinking about draining a couple of feet out of the pool and adding water to drop the CYA level. I do not want to have to go through this next season when people are actually swimming in the pool.

25,000 Gallon gunite, Hayward 220ST filter, 1 HP pump.

[Schooled by Pool]

Update: I have been keeping the Chlorine level high, 10+ FC with an occassional shock. It is still cloudy. But, I can see the bottom of the shallow end and it looks like I can see about 5 ft. down into the deep end. I have been brushing the walls, and I vacuumed over the weekend. Hoepfully, we are close to the end of this mess.

Last night I shocked the pool again. Before I shocked, the pool was 16.5 FC, .5 CC, 7.6 ph, 110 TA, 370 CH, 150 CYA. I added 4 gallons of liquid shock from a pool store (Unstabilized chlorine, 10% or 11% depending on which part of the label you read. Up until now, I have been using store bought chlorine (6% Dollar General)). I have gone through a lot of chlorine and want to try a higher concentrate with less bottles.

After I shocked pool, I tested the FC 2 hrs later. It was 27.5.

This morning I tested. It was 27.5 FC, 0 CC, 7.8 ph. 120 TA, CH 370. So the ph went up, which was odd. But, the other odd thing was when I tested the TA, it turned from green to a pale yellow color, rather than a pinkish red color. I tested it twice, same results. Why did the color change? Also, why did the ph go up?

I am assuming all the algae in my pool is dead and I am waiting for everything to settle, due to the FC and CC. Is there anything else I need to do before I get someone to shut down the pool for the winter?

Thanks for your help.

[PoolDoc]

membership updated . . .

[Schooled by Pool]

Update: The previous evening I brushed and shocked. The next morning I had no change in FC & CC readings. Last night, for the sake of being throrough and aggressive, I brushed and shocked again, bringing the FC level up to 32. The FC dropped to 28 this morning, and CC was at 1. I suppose this means I still have algae to contend with? I will shock again tonight.

On another note, I spoke to the builders of my pool and they sent me a copy of the original blueprints. It is 16 X 40, 24,811 gallons (I was close in my estimate). Pool is older than I thought....35 years.

Hayward 220ST filter, 1 HP pump.

[aylad]

The pH went up because your chlorine level is so high--chlorine levels above about 15 ppm on the Taylor kit will give falsely high pH levels, so don't adjust your pH any until the chlorine comes back down and you get a reliable reading. I suspect that's the same reason that your TA changed colors the way it did.

If you are still losing 4 ppm of chlorine overnight, then you are indeed still fighting something in the water. Maintain your shock level until you don't get an overnight drop, and then you should be ready to close the pool.