Liquid Chlorine Shelf life vs Effectiveness

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Gopherboy6956

Gopherboy6956

Well-known member
Jun 3, 2020
92
Fargo, ND
Hey all - I just wanted to come here for a little more information from the community that I haven't been successful finding on my own.
I've read that chlorine starts to break down relatively quickly on the shelf, and will be less effective over even a few months on the shelf.

My main question is this. If I used, lets say, year old chlorine in sealed bottles, will A or B happen:

A - the chlorine will report normally when doing a free chlorine test, but will just not be as actually effective
B - the chlorine will report lower numbers than fresh chlorine in regards to the test

I wanted to do a SLAM, and had two cases of 12.5% sittng on the shelf from last year - so wondering how effective that might be.

Thank you!
 
Chlorine is chlorine. The idea of “effectiveness” is not scientific. Chlorine kills at a specific rate that is dependent on its concentration. Chlorine breaks down over time (mostly forming oxygen gas and chloride salt) so old chlorine is simply less concentrated chlorine. But as long as the FC is at a specific level, it doesn’t matter of you use old chlorine or new chlorine to get there … it just takes more old chlorine to get to the same point.
 
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What I don't see addressed in the article and posts is the difference in breakdown between sealed and unsealed bottles. If I need to use a quart out of a gallon jug, how much faster will the remaining chlorine break down since it was exposed to air?
 
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There are no such thing as sealed bottles. All liquid chlorine is sold with “breathable” caps on the containers. This is because chlorine breaks down and forms oxygen gas. If the container were completely sealed, it could/would burst. That would make it a transportation hazard.
 
You can always test the strength of your chlorine by diluting 10,000 to 1 - Put 1ml of bleach in 100ml of distilled water, mix well, then take 1ml of that and mix into another 100ml of distilled water. Then test this mixture with your test kit like normal. Whatever ppm you get as a result is equal to the percentage in your jug.
 
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I tested my chlorine by adding 3ppm, testing before and after and then adjusting the chlorine % on the poolmath app set to add 3ppm until my oz matched what I had poured in.

My 6 month old 10% chlorine is testing at 6.5% and I'm wondering if in addition to having to add more to get to the same ppm level if old chlorine get used faster?
 
garroyo130 said:
My 6 month old 10% chlorine is testing at 6.5% and I'm wondering if in addition to having to add more to get to the same ppm level if old chlorine get used faster?
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No it will not get consumed faster. You might be adding less effective % of chlorine, but it will not change the consumption rate.
 
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JoyfulNoise said:
There are no such thing as sealed bottles. All liquid chlorine is sold with “breathable” caps on the containers. This is because chlorine breaks down and forms oxygen gas. If the container were completely sealed, it could/would burst. That would make it a transportation hazard.
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I guess I disagree with that. All my bottles have a spill-proof adhesive seal under the cap. Its definitely not breathable.
 
Gopherboy6956 said:
I guess I disagree with that. All my bottles have a spill-proof adhesive seal under the cap. Its definitely not breathable.
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Look at the adhesive safety seals. There’s probably a very small circular patch near one side that looks like this -

1685107214722.png
Any liquid chlorine will have something like this or the seal itself will be made of a multilayered breathable material. You absolutely can’t seal LC in a bottle, it’s a burst hazard. Even store bought bleach has caps that don’t fully seal to prevent bursting.
 
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JoyfulNoise said:
Look at the adhesive safety seals. There’s probably a very small circular patch near one side that looks like this -

View attachment 496371
Any liquid chlorine will have something like this or the seal itself will be made of a multilayered breathable material. You absolutely can’t seal LC in a bottle, it’s a burst hazard. Even store bought bleach has caps that don’t fully seal to prevent bursting.
Click to expand...
Hmm, i'll have to look at my bottles. I would never have noticed that. I use Pro-Clor 12.5% from menards - and looking at the bottle it appears you're correct. Crazy!
2796950.jpg
 
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