How much chlorine should my pool be using?

[Yeggim]

...I don't know where you live but if you find after awhile that with a CYA of 40-50 you continue to have trouble keeping chlorine in your pool, then it may be appropriate to take it a little higher. Aylad (another one of the mods) lives in LA and her pool is in hot full sun all day. She deliberately runs her CYA at 80-90 (or maybe 70-80, I can't remember which) because without doing so, she can't keep a FC reading. This also allows her to only add bleach every second or third day instead of daily. Watch your pool's pattern for a few days and report back and we'll help you decide what is most appropriate for your pool....

The last week or week and a half, I've backed testing off to every other morning, and occasionally in the evening. Both times, I haven't added bleach until the chlorine level was down to the .5-1 range - I think each of those times, I tested two days before and had chlorine around 5 or 6, then a couple days later, dang near nothing.

Watermom hits the nail on the head. I have a CYA range similar to yours. I lose about 2.5 ppm FC per day. Your pool seems to behave the same as mine. With a CYA like yours and mine, we have to stay between 3-6 ppm of FC. We can't go below 3 but it's alright to go a little over 6.

You don't have to test everyday and you don't have to add chlorine everyday. I add chlorine everyday and I'll explain why. Let's say we want to make 4ppm as our lower limit and that's what our test says we have in our pool on Monday evening. To make it to Wednesday evening, I'll have to add at least 5ppm because I lose 2.5 ppm per day. That means there will be 9ppm of FC in the pool Tuesday morning. That's not a real problem with CYA near 50 but I have little guys that like to swim early in the morning. I would have no problem letting them swim with 9ppm but it's no trouble for me to add 2.5ppm every evening. That puts me at 6.5ppm. That's enough wiggle room if the wee ones weedle in the pool.

Right now it looks like you have to add a gallon of 6% Bleach a day or 2 gallon every other day. Don't do like I did last year. Get the FAS/DPD kit to test chlorine. Believe me, it will pay for itself and save you from a lot of headaches. With this kit you'll be able to get your pool patterns down pat. When or if you have to shock, you'll know exactly where your at and exactly when to come out of it.

[DistantHorizon]

Ok, well, I ordered the FAS-DPD test kit ( http://www.amazon.com/gp/product/B003V54GUG ), but it won't be here until Wednesday. Also ordered more CYA test ( http://www.amazon.com/gp/product/B0002IXIZE ).

In the meantime, with the expectation that I'll have to add CYA, and knowing that the pool uses chlorine, I put a dozen 3" tabs in the skimmer basket (knowing they take several days to disolve). Ran the pump continuously with tabs in for about a day, with the plan to remove the tabs when pump was off.

Was time to backflush last night (my spider gasket was still jacked, and pool guy hadn't dropped by yet), backflushed and rinsed. Took apart the multiport, tried to reseat gasket, got things working though backflush hose was still trickling.

Checked chlorine and CYA last night (diluting 50% with distilled water), read 2-4 on the scale, so figured it was 5 or 6. Knew that tends to drop, so took out tabs, disolved a pound of dichlor in a bucket and put it in (for target of 8, and to add a little CYA). Hooked automatic pool cleaner to the skimmer and let it run overnight.

This morning I went to get a spider gasket, and took a sample to a pool store who I at least think knows how to test properly. Chlorine was 8 (which was what I'd targeted), but they said CYA is over 100!





She let me see the test for myself (they had the more expensive dipstick-in-tube test).

In the past, one pool store has tested it at 100+ 3 times, 30 once, and 40 once. When I tested last night, I read about 42, which corresponds with the 40 I read a couple weeks ago (I have the Taylor K-2005 CYA test), but as with all the color-match tests, I wasn't completely confident I was reading it right. The previous pool owner appears to have used 3" tabs and dichlor exclusively, which would point to high CYA.

I just did my own test again, and got a little higher reading, 45, than I did before I added dichlor and tabs, so if I'm misreading, I'm doing so consistently.

Question one: Did CYA test high because I've been adding it recently (added dichlor the night before, and ran 12 3" tabs for a day before that)? Or is my CYA really that high???

Question two: Edit - researched on this forum, indeed I did get pool-stored. Going to try to return this stuff, no need to answer this question. The pool store said my phosphates are 300, and that could be eating my chlorine. Is that true? I didn't think fast enough, and got pool-stored into a $40 jug of phos-free, but I haven't added it yet. Don't know if I can return it or not...

Right now it looks like you have to add a gallon of 6% Bleach a day or 2 gallon every other day. Don't do like I did last year. Get the FAS/DPD kit to test chlorine. Believe me, it will pay for itself and save you from a lot of headaches.

Gah, all that bleach sounds like a lot of $, but if that's what it takes, then that's what it takes. We'll have to see how my CYA issue turns out. As for the kit, yeah, went ahead and ordered.... wish I'd ordered a better CYA test rig too.

[Watermom]

Don't panic. Your CYA test is more likely to be accurate than their dipstick-in-tube test. The disappearing black dot test is the only one we trust.

So, if you are getting 45ish for your CYA reading, assume that is correct. What goal are you shooting for? Typically we suggest 40-50. if that is what your target is then remove all pucks from your pool and also don't use any more dichlor. A week after the last dose of any stabilized chlorine, test your CYA again, but not before. Then, post a full set of numbers here and we'll make a recommendation for you from that point.

[DistantHorizon]

The saga continues! On a positive note, the pool store took back their silly Phos Free, so that's $40 back in my pocket.

Went to another pool store where CYA scored a 70! Apparently I can get whatever numbers I'd like just by getting different people to test, lol! Chlorine had dropped a whole ppm, from 8 @ 9am to 7 @1:30pm, part of which I might write off to testing inaccuracies.

I guess irregardless, my pool IS running fairly well. I seem to lose a lot of water to evap, and it seems to get a lot of dirt in it; but water has been clear for IIRC, a couple weeks now.

Don't panic. Your CYA test is more likely to be accurate than their dipstick-in-tube test. The disappearing black dot test is the only one we trust.

So, if you are getting 45ish for your CYA reading, assume that is correct. What goal are you shooting for? Typically we suggest 40-50. if that is what your target is then remove all pucks from your pool and also don't use any more dichlor. A week after the last dose of any stabilized chlorine, test your CYA again, but not before. Then, post a full set of numbers here and we'll make a recommendation for you from that point.

I don't know what I should be shooting for. I figure I can shoot for 45-50 or 70ish, but I don't know which. I am uncertain of which will be cheapest. I wouldn't mind running higher levels, but it seems that shocking would be fairly expensive and hard on swimsuits.

I will not add any more CYA (though I lost a little this morning to a fairly long backflush) for another week, and I'll post numbers with my brand new CYA reagent bottle.

[Watermom]

Losing 1ppm if it was really sunny wouldn't be unusual. You're gonna lose chlorine and that is fine. CYA helps protect it but losing it during the day is to be expected. Plus, as the chlorine does its job of sanitizing the water, it is also depleted.

If our CYA is 45ish, I'd leave it there for now. If you find that you can't keep chlorine in the pool, you can always add more. Don't bother having anyone else test it for you. YOU will do a better job than any pool store. As far as having to shock harder --- you use more chlorine at a time but don't have to add it as often so it balances out. And, high chlorine with high CYA is not any harder on swimsuits than low chlorine and low CYA. It is the same.

[DistantHorizon]

Jun 25 morning, FC 8, pH 7.4
Jun 25 evening, FC 7

Jun 26 morning, FC 6, pH 7.2, TA 110
Jun 26 evening, FC 5+ (didn't bother to dilute), pH 7.2

Jun 27 evening, FC 5, pH 7.2; added 52oz 6% bleach for target FC 6
Jun 28 evening, FC 5, pH 7.3/7.4; added 52oz 6% bleach for target FC 6

On Jun 29, I received my FAS/DPD test kit! Also new CYA reagent, but it hasn't been a full week since adding stabilized chlorine.

Jun 29 evening, FC 5.5, pH 7.6, CC maybe .5; added 2.5oz cal hypo for target FC 6/6.1

Jun 30 evening, FC 4.5, pH 7.4, TA 110; added 7oz cal hypo for target FC 6.1.

Since I've been uncertain about CYA, I made the decision for now to just try to keep FC between 5 and 6, since 5 is above the minimum on the the 60-90 range of the Best Guess chart.

What do you all think about these numbers? I guess the only thing I notice in looking over them is that FC dropped quickly again from Jun 29- Jun 30... but I'm thinking maybe the Pool Calculator's 2.5oz recommendation was a little low.

Thanks again for all the help.

[Watermom]

Your numbers look fine. Post your CYA level when you test for it.