How quick does chlorine dissipate?

May 12, 2008
51
California City, CA
I had trouble at the end of last year with keeping my Free Chlorine level up. On Monday my FC was almost nothing and my TC was 2. I put in all the bleach I had in my house on Monday evening. Since then, my FC has been around 4.7 and my TC has been 4.5. During this time I've had my chlorinator running about 3 hrs per day at 100%. My pool water is covered with a solar cover and the pool temp is about 78 degrees. Would the chlorine have gone down if my chlorinator hadn't been working? How long does it take for the chlorine to dissipate if no new chlorine is going in?? I want to make sure my chlorinator is working.
 
Chlorine goes down from sunlight and from keeping the pool clean. The rate that it goes down from sunlight depends on your CYA level and how sunny it is. A solar cover greatly cuts down the amount of sunlight reaching the water, so far less lost to sunlight with a cover.

If you post a full set of test results, we can probably give a more specific answer.
 
Today's numbers were FC 3.0, TC 3.0, PH 7.6, ALK 125, CYA 35. Does that help at all?
Yes. You should probably bring your CYA up to aroun 60ppm or so per SWG's recomendations. Most of them suggest about 60-80. That'll cut down your FC loss..

Secondly, I would suggest an overnite FC loss test. If you need info on how, post back. It'll determine if you have organic material in the pool.

Third, how does your water look?
 
I just added more stabilizer this morning to bring my CYA level up. But it's granular and that takes awhile to take effect, correct? Also, I would love to know about the overnight free chlorine loss test. Is that when you check in the am to make sure the numbers stayed the same overnight?
 
Yes. You test the FC level after sunset and at least 30 minutes after the final chemical addition. Then you measure the FC level again as early as possible the next morning. If the FC level goes down between the two tests by more than 1, something is growing in your water and you need to shock.
 
I did that this week and it stayed the same. By the water, my water is clear as can be. Unfortunately, since it's a fiberglass pool and I shocked it to get rid of whatever was keeping my FC from matching my TC now my stain is back. I added a bottle of purple stuff but I'm probably gonna have to do an ascorbic acid treatment to get the rest of the stains out. I don't want to do that until my CYA is up to what it's supposed to be. I added more stabilizer today, how long until it's completely dissolved and I can check my CYA?
 
It is best to give CYA a full week to dissolve before testing it again. Most of the CYA will dissolve in the first 24 hours, but the level can sometimes continue creeping up for several days to a week.'

Sometimes, if you add sequestrant quickly enough, you can get new stains to go away with just sequestrant. Otherwise you will need to do the full ascorbic acid treatment.
 

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templehb said:
it's a tea colored stain, the entire pool under the water line, worst at the steps. Everyone keeps saying it's from metals but I've never gotten any positive testing for metals in my water. I just use the ascorbic acid and it goes away, but never for very long.

I know it's wierd, but when the pool is stained, the water won't test positive for metals. When you put in the sequesterant, the stain lifts and is "in solution" and then the water will usually show metals present. Bizarre, I know. :wink:
 
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