How to test bottled bleach?

[aylad]

Shoppers Food Warehouse in Washington DC is selling now the HomeBest brand of regular bleach but does list the chlorine concentration. Is there a way to test it using Ben's kit?

There's usually a 1-800 number on the bottle, you could call them and ask what the percentage is (or at least what it's supposed to be!)

Janet

[CarlD]

Yes, you CAN test it. Somewhere around here is the work I did last summer on this.

If you add (as I remember) 1.8ml of bleach to a 5 gallon bucket of NON-pool water, you can test the concentration.

The idea is that if one gallon of 6% bleach adds 6ppm of FC to 10,000 gallons, then 1.8ml (?) adds the same concentration to 5 gallons.

If you simply do the division and conversion it works.

And if you do it ALL in metric, then 1ml of bleach added to 10 liters of water should give you the same 1 : 10,000 concentration.

Then you measure the bucket the same as the pool and the result is the concentration in the bleach bottle.

The PS-232 had something that measured the 1.8ml...again as I remember before senility sets in.....

[Ohm_Boy]

It's almost certainly 5.25% or 6%

I've seen some 3% off-brands around, and I think I recall seeing even less - like 2.something% in Kroger.

If they won't even print the concentration, I'd be real leery of it.

[KurtV]

I've seen some 3% off-brands around, and I think I recall seeing even less - like 2.something% in Kroger.

If they won't even print the concentration, I'd be real leery of it.

Your right, ohm; I'd forgotten about that 3% stuff.

Regardless, my main point remains: You have to see what the the stuff does in your pool anyway. Depending on how long the bleach has been sitting on the shelf at the store or in your laundry room it will almost always contain more or less active ingredient than is on the label; sometimes significantly more or less.

After a while you get an idea which stores move the stuff fast enough to always have "fresh" bleach available and which brands (or off-brands) give you what the label says it will. That will give you a good idea what a given bottle of bleach will do to your chlorine level but it will always be a bit of a crapshoot. Fortunately, even the limited accuracy/predictability we have is almost always good enough. For e.g., it doesn't really matter whether you have 3.2 ppm or 4.5 ppm so long as you keep it between the 3 and 5 (or whatever the best guess chart calls for in your case). If you dump in a bottle and only get half the chlorine you thought you would, dump in another bottle. No big deal. That's one of the reasons we test often.

We sometimes forget that the whole point of using Ben's Grocery Store Chemicals pool care method is to keep a clean, safe pool at a reasonable cost and with minimal hassle. Trying to test the chlorine strength of a bottle of bleach is distinctly not in the minimal hassle category to me (though it's an interesting academic exercise in and of itself).

[crsuarez]

thanks for all your answers...

[JohnT]

I've seen some 3% off-brands around, and I think I recall seeing even less - like 2.something% in Kroger.

If they won't even print the concentration, I'd be real leery of it.

Kroger carries a 2.75% bleach.

[crsuarez]

ok, CarlD's directions worked...i used 1.8ML of the HomeBest bleach in between 10 and 17 litters (I just poured water into a 17 litter bucket without filling it) of non-pool water and I got a reading of 9ppm. Without being accurate I would think that the strength of the bleach is 5.25 or above and not 3%, correct?

[KurtV]

ok, CarlD's directions worked...i used 1.8ML of the HomeBest bleach in between 10 and 17 litters (I just poured water into a 17 litter bucket without filling it) of non-pool water and I got a reading of 9ppm. Without being accurate I would think that the strength of the bleach is 5.25 or above and not 3%, correct?

Probably. If you used city water to dilute the sample, it probably had something less than 4 or so ppm free chlorine (I think 4.5 is the recommended max). My tapwater is usually about 2 ppm FC and 1 CC (chloramines are actually used for sanitation of drinking water).

[hamop78]

I test every batch of bleach I buy ---- Using 1000 ml (1 Liter) of UNCHLORINATED water (from a well or distilled), place .1 ml of the sample from your bleach bottle -- mix and test.

As for the dilution method for testing bleach I use a 1000 ml volumetric flask and a medical syringe used to perform the standard tuberculin “Tine” test. The syringe has a total capacity of 1 ml but is graduated in .01ml graduation intervals with major graduations at .1ml. The dilution method is accurate within .1 ml @20 deg C.
Testing is done using the FAS-DPD method, using a 25ml sample size, again yielding accuracy within .2 ppm in a 10000 to 1 dilution.

I have found the results to be repeatable with a 95% confidence level (in scientific terms [95 out of 100 tests]).

The results of the test is equal to the percentage of bleach.