Liquid Chlorine from last year..

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Danylukburton

Member
Jul 17, 2020
20
MA
Hi All,

Will it hurt to use liquid chlorine leftover from last year? I realize that it will have degraded, but at any point does it become something else completely and is unsafe? I was reading someone was saying it's mostly lye after a year?

If it is safe, can I assume 12.5% LQ purchased last Aug (and stored inside in an unheated basement all winter) is about half the strength or less then when it was bottled and add for say 6% level and test and go from there?

One other thing.. I had one old bottle that had just a few ounces left. I took it out of the tote I had it in and put it on the concrete basement floor a few days ago. Today I noticed some condensation on the bottle. Is that expected? Can I pour those remaining few ounces in my pool or is there some issue with it? Thoughts?

Thanks for any advice or help!
 
I order a 55 gallon drum of 12.5% every year, and it serves to get my pool up and going the next spring as well.
As a matter of fact, I JUST received my yearly supply this morning. I opened my pool on Easter weekend, and my old batch has done fine until now.
It gets refilled when the level gets low enough to accept another barrel.
 
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If you are willing to do a little bit of volumetric analysis, ( and you are extremely bored and want to feel smart ) you can find out experimentally! Just test your water after sundown, carefully measure and add, from an UNOPENED bottle, what NORMALLY ( according to PoolMath ) would raise your pool water by 1 or 2 ppm FC (preferably 2 for more accuracy), let your pump run for 30 minutes and test FC again. Assuming that your pool volume estimate is reasonably close, you will be able to see if, and how much, the strength has degraded. You might have to use the 25ml sample size ( 1 drop = 0.2 ppm ) for the FAS/DPD to get enough accuracy. Once you know how much the FC percentage in your liquid has degraded, you can adjust your volume to use accordingly.. ie. expecting +2ppm and you only get +1ppm, then your liquid has degraded to 6.25%. It is probably safe to assume that all unopened stored bottles have degraded by the same amount.

no idea.jpg
 
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Danylukburton said:
Hi All,

Will it hurt to use liquid chlorine leftover from last year? I realize that it will have degraded, but at any point does it become something else completely and is unsafe? I was reading someone was saying it's mostly lye after a year?

If it is safe, can I assume 12.5% LQ purchased last Aug (and stored inside in an unheated basement all winter) is about half the strength or less then when it was bottled and add for say 6% level and test and go from there?

One other thing.. I had one old bottle that had just a few ounces left. I took it out of the tote I had it in and put it on the concrete basement floor a few days ago. Today I noticed some condensation on the bottle. Is that expected? Can I pour those remaining few ounces in my pool or is there some issue with it? Thoughts?

Thanks for any advice or help!
Click to expand...
It’s probably a little less potent but just fine.
 
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The chlorine basically just degrades into salt water. It’s not going to hurt anything.

For what it’s worth my 12.5% left from last Summer that I used this spring was still raising levels like I’d expect 8% bleach to do. Cool storage (basement in my case) makes a big difference I think.
 
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Scripps Research Institute claims it degrades in strength by 20% per year of storage:

We could use their claim as our hypothesis to be tested, namely:
1. Unopened liquid bleach of known initial strength will degrade by 20% after 365 days of storage in its original container
 
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