Quote Originally Posted by chem geek View Post
bbse,

This link has a table near the bottom of the webpage that shows that the half-life of more concentrated chlorine isn't very long. At 12.5% and 80F temp, the half-life is around 150 days (5 months) so it really needs to be used within a month or two to be economical. If you can keep it at cool temps, then that helps a lot.

Richard
Hi Richard

5 gallons of 15% will cause a theoretical raise of 75ppm in a 10,000 gallon pool. 5 gallons of 14% 70. 5 gallons of 12% of 60ppm . 5 gallons of 10% 50ppm raise. 5 gallons of 8% 40ppm. 5 gallons of a 6% solution 30.

I've still got to fill my 5 gallon carboy with the greater than 12% solution. But when I do I plan to get a sample and see what real world measurements would be like.

So if you have a daily consumption rate of 1.5-4ppm then you end up using 5 gallons of 12% solution up in 40 days or shorter. I would imagine utilizing a solar cover could increase the length of time that you'll have your 12% bleach around.

But even if you kept the 12% around for 5 months (to reach the half life that you stated at 80f) wouldn't you still end up somewhere around 45ppm increase for 5 gallons over 5 months? Which would round out somewhere to a near equivalent of 9% (ish) over 5 months for a starting 12% solution.

But I thought that bleach was supposed to become more stable with every bit that it weakens. (Where) if you start with a 12% solution it will take longer to degrade from 12% to 11% than it would from 6% to 5%...and also the same would hold true from 11% to 10%, no? (I'm just thinking aloud here...and asking questions so I can understand a bit better) If this is true...then wouldn't it be difficult to predict how much a 12% solution would degrade over 3 months?

(if the above is true) Wouldn't the rate at which bleach weakens actually increase (in length of time) for each percentage loss. I would think that this would give you a slightly better cost/effect ratio even if it were drawn out to the 5 month time period. Now, if you used up the 5 gallons in three months I would think it would even increase more.

just thinking aloud
thanks,
dan