Thermal decomposition of stored bleach

[Water_man]

0.2 ml is about 4 drops. Although by your routine you dilute 1 by 10,000 as chem geek suggested, you compromise on the accuracy significantly by dropping in only 4 drops.
I wouldn't measure anything less than 1 ml - that's about 20 drops. You can do two dilutions of 1 ml into 34 fl oz and you get your 1 in 10,000 dilution.

[CarlD]

0.2 ml is about 4 drops. Although by your routine you dilute 1 by 10,000 as chem geek suggested, you compromise on the accuracy significantly by dropping in only 4 drops.
I wouldn't measure anything less than 1 ml - that's about 20 drops. You can do two dilutions of 1 ml into 34 fl oz and you get your 1 in 10,000 dilution.

I'm not using drops--the eyedropper is marked off in .1 ml units, but starts at .2 ml. It's a marked line. Besides, if my LC tests at 15% or 12% I don't care--schocking your pool isn't an exact science nor does it need to be. But, like horseshoes and hand-grenades, close is good enough.

But if the LC has degraded and tests at 5%, it will certainly be captured.

Besides, for greater precision, using my method, all you need to do is pour five of those 2 liter soda bottles worth of tap water into a five gallon bucket and use the eyedropper at the 1.0 ml level. Takes a little longer.

[mas985]

Our water district uses CC instead of FC so you might want to check that as it will throw off the measurement. According to my brother in-law who works at the regional water district, quite a few plants do this. So you might want to use distilled water instead of tap water or pre-shock the tap water and let the chlorine drop a bit before the test.

[CarlD]

Our water district uses CC instead of FC so you might want to check that as it will throw off the measurement. According to my brother in-law who works at the regional water district, quite a few plants do this. So you might want to use distilled water instead of tap water or pre-shock the tap water and let the chlorine drop a bit before the test.

I'm not sure I understand this--if you are testing your LC/bleach for its strength, you want to test FC. I'd be shocked if CC > 0 shows up.

CC is a perfectly reasonable test of tap water to see if there's some contamination of that resulted in a CC > 0.

[mas985]

My point was to make sure that there is no CC in the tap water or the results may not be very accurate.

Chemgeek had mentioned that one should measure the FC of the tap water before adding the LC which is a good idea but many water districts use CC instead of FC in tap water, it lasts longer. This could cause a significant error in the LC measurements if not taken into account. Adding FC to tap water with CC will convert some of the CC into FC but from what I understand about the process, there is a net loss of FC.

So if you use tap water with CC and then add LC, it is likely to underestimate the strength of the LC. I am sure that Chemgeek has a way to take the CC conversion into account but it may just be easier to avoid it all together buy using distilled water or water without any CC.