Old Bleach At Walmart?

[countrygal]

I just purchased 10 large jugs of 6% bleach from walmart and poured enough in(5 jugs) to raise the FC to 18 based on the Pool Calculator's estimate. After 2 hours I tested the water and the FC level was 7 with 0 CC, I got the same results after the third hour. I just opened the pool and it was rather clean so I did not expect to loose FC that fast and its a cloudy, rainy day so the sun could not play a factor. I am thinking that I got a bad batch of Bleach from Walmart or that the powder in my Taylor Test Kit T-100 could be bad, its about 3 years old. Has anyone heard of the quality of Walmarts Bleach or how long the life expectancy of the test kit chemicals is? In any case, I just added the other 5 jugs (before I thought about the test kit being the problem) I am either going to be ok or I just made a very bad mistake.

[chem geek]

It's possible for the bleach to have lost its strength, though usually it lasts quite a long while unless it was in the sun or otherwise stored at high temps. Chlorinating liquid at higher concentrations loses strength much faster. The table at the bottom of this page gives the half-life of chlorine at different concentrations and temperatures.

It's also possible for your pool water to have nascent algae growth that wasn't visible or to have other chemicals in it that needed to get oxidized that used up the chlorine. If you take a clean 2-gallon bucket and add tap water to it, then 1/4 teaspoon of 6% bleach would be 10 ppm FC so you can do that to test the bleach. Just measure the tap water first since it may already have FC or CC so you need to take that into account. If the tap water registers the expected amount of chlorine but pool water does not, then that means the pool water had something in it for chlorine to oxidize.

[countrygal]

Thats great, just what I was looking for! I need to get more tomarrow and I will test it. Last year I bought my bleach from the Dollar store and I really got some strange readings so this year I switched to Walmart and got concerned when I saw a 68% loss in FC after 2 hours, most likely I just had a lot of stuff in the pool but it will be nice to be able to double check the bleach. Again thank you.

[Swim 'N Save USA]

you must also remember, Walmart is open 24 hours a day. All those chemicals are sitting under fluorescent lights (UV) that whole time which degrades it's effectiveness drastically.

[chem geek]

I presume that the bleach is in opaque bottles so the light from the fluorescent lights should not be a problem. Also, the UV generated in a fluorescent is mostly converted to visible light by the phosphors in the lamp. I've never heard of anyone getting suntan under normal fluorescent lights.

There are many people reporting on other forums that they buy bleach at Walmart and have not had any problems so this seems to be an unusual case. It can certainly happen and is more likely to be caused by extreme high temperatures, including bottles sitting out in the sun getting warmed up, perhaps during transportation or temporary storage, though that is not normal.