Bleach shelf life?

[gtnos]

How long will my bottles of 8.25% bleach last? I normally just pick up a few bottles when I go do our family grocery shopping every 2 weeks throughout the year so that by the time pool season starts, I have my bleach for the season.

the bottles are stored upright on shelves in my wooden shed year round.

 

[Smykowski]

Light and heat are the enemy. The darker and colder your storage place, the longer it will last. Search for "bleach shelf life," chem geek posted a great article a few years back that can answer your question better with numbers.

 

[gtnos]

found it:

http://www.troublefreepool.com/threads/20022-Shelf-life-of-bleach

it does a good job explaining it, BUT, one question I still have that it didnt answer:

exposure to summer heat obviously causes strength degradation, but what about extreme cold?

if I buy 8% in december when its cold, will it still be 8% come about now..?

 

[chem geek]

As shown by the table at the bottom of this link, the rate of degradation is a function of both temperature and concentration. For 8.25% bleach, figure losing about half its strength in 6-7 months at 90ºF but a year at 80ºF so keeping the chlorine cooler helps a lot. This assumes the chlorine is of high quality with no metal impurities that speed up its degradation.

As for cold, that is not a problem and I'm assuming you aren't talking about freezing.

 

[gtnos]

As shown by the table at the bottom of this link, the rate of degradation is a function of both temperature and concentration. For 8.25% bleach, figure losing about half its strength in 6-7 months at 90ºF but a year at 80ºF so keeping the chlorine cooler helps a lot. This assumes the chlorine is of high quality with no metal impurities that speed up its degradation.

As for cold, that is not a problem and I'm assuming you aren't talking about freezing.

awesome. Thanks chemgeek! And no, even when it gets freezing temps outside, I have not yet had the bleach itself freeze in the shed.

 

[BoDarville]

The freezing point of 8.25% bleach is around 15°F, so you have plenty of margin once air temps dip below 32°F before you need to be concerned about the bleach freezing.