Old Bleach

[rjg202]

So I stocked up on WM bleach in the last few weeks, but then I found 5 large jugs I guess I got last year in the garage where my wife kindly put them in a cabinet. So After doing Liquid Chlorine 12.5% to open I switched to the 6%, I don't seem to be seeing the chlorine increase as much as I did last year. Does unopened bleach if stored in a cool garage lose it potency over 8 months? I am adjusting through it, but figured I'd ask. I am confident I can test and adjust as needed. I think once I use all the bleach I may move to 12.5% from pool store, I figure it costs me 25 cents more a day since I use 1/2 as much and the price I get it with a discount for buying 4. MY 3 local WM's get cleaned out of the big bottles this time of year and I have mixed feelings on Dollar store stuff and the strength of it being consistent, ironically that is what I am asking about.

Also, how long after adding chemicals can one test in a 12,000 gallon pool? 2 hours? I've seen different specs for my pool from 10,500 to 12,000 gallons, so recently I've been estimating at 12,000 gallons.

Thanks

 

[Butterfly]

So I stocked up on WM bleach in the last few weeks, but then I found 5 large jugs I guess I got last year in the garage where my wife kindly put them in a cabinet. So After doing Liquid Chlorine 12.5% to open I switched to the 6%, I don't seem to be seeing the chlorine increase as much as I did last year. Does unopened bleach if stored in a cool garage lose it potency over 8 months? I am adjusting through it, but figured I'd ask. I am confident I can test and adjust as needed. I think once I use all the bleach I may move to 12.5% from pool store, I figure it costs me 25 cents more a day since I use 1/2 as much and the price I get it with a discount for buying 4. MY 3 local WM's get cleaned out of the big bottles this time of year and I have mixed feelings on Dollar store stuff and the strength of it being consistent, ironically that is what I am asking about.

Bleach loses strength over time, more quickly when it has a higher percentage and when it is stored at higher temperatures. You should store bleach in a cool dark place. 6% bleach can reasonably be stored for about six months. 12.5% bleach can reasonably be stored for about one month. After that time it is still usable, but will have lost some of it's strength. And you are right to stay away from the dollar store bleach.

Also, how long after adding chemicals can one test in a 12,000 gallon pool? 2 hours?
An hour is fine.

I've seen different specs for my pool from 10,500 to 12,000 gallons, so recently I've been estimating at 12,000 gallons.

Thanks

 

[scottja]

Regarding Bleach shelf life,
It becomes about 1/2 strength over 6 months to a year depending on storage temperature.
So 12% becomes 6%... 6% becomes 3%. etc.