Info from Clorox on using their bleach for pools

[chem geek]

I did give some more info (suggestions, if you will) and asked to communicate with a technically knowledgeable person in manufacturing, but we'll see what comes of that. I agree with you that it was nice of them to at least respond, though I believe it is a standard response triggered by my use of the word "pool" which I had in my initial inquiry.

In the meantime, I did some quick research at some stores today and found that bottles of Clorox Regular bleach say 6.0% Sodium Hypochlorite and below that it says 5.7% available chlorine. So that strongly implies that the 6.0% is a weight % of sodium hypochlorite while the 5.7% is the weight % of available chlorine as defined in terms of the molecular weight of chlorine gas (which has, by definition, 100% available chlorine). This means that neither number is "Trade %" (grams available chlorine in chlorine gas molecular weight per 100 ml) which in this case would be about 6.2% and would be the number to be used in any simple volume scaling calculations (e.g. BleachCalc).

I also found chlorinating liquid that said 10.0% Sodium Hypochlorite which would imply a Trade % of about 11.0%. On the other hand, my recollection is that the chlorinating liquid I have been using says 12.5% and I believe that to be Trade %, but am not certain. Damn, this is SO confusing -- why did they even come up with this thing called "Trade %" anyway? I know that it makes volume-based calculations of ppm simpler, but it's one more way to accidentally mislabel a product!

I'll keep y'all posted (I can hear the yawns from here).

Richard

[hamop78]

Richard,
I bought 4 cases (3 X 182 oz jug) of Clorox Ultra last weekend at Sam's --- the price worked out to 1.0333 cents per oz. I tested the product using the .1ml per 1L distilled water and got 6.8% using FAS-DPD w/25ml sample size. This reflects a higher percentage than they claim on their MSDS. I test every batch I buy. If I get a low batch --- Back it goes .

[chem geek]

Richard,
I bought 4 cases (3 X 182 oz jug) of Clorox Ultra last weekend at Sam's --- the price worked out to 1.0333 cents per oz. I tested the product using the .1ml per 1L distilled water and got 6.8% using FAS-DPD w/25ml sample size. This reflects a higher percentage than they claim on their MSDS. I test every batch I buy. If I get a low batch --- Back it goes .

Just so you know, and now that we have all the terminology to get hopelessly confused, the 6.8% that you determined through the "volume" method is a "Trade %" since the FAS-DPD test measures ppm of chlorine as "available chlorine as ppm chlorine gas" and "Trade %" is "available chlorine as ppm chlorine gas per 100 ml".

The "Weight % Sodium Hypochlorite" is 6.5% and is within the range on the MSDS of 6-7.35% (which is a hell of a range!). You can convert from "Trade %" (i.e. your test measurement) to "Weight % Sodium Hypochlorite" by multiplying by 74.4422/70.906 = 1.05 and dividing by the specific gravity (density) of the liquid which is 1.1 for Clorox Ultra.

When comparing prices, you can factor the price per ounce by dividing by the "Trade %" (and multiplying by 100 for a reasonable scale) so in your case that is 15.2 while my source is 15.6 so is fairly close in price for what we are getting (though I carry less weight ).

Richard

[waterbear]

In the meantime, I did some quick research at some stores today and found that bottles of Clorox Regular bleach say 6.0% Sodium Hypochlorite and below that it says 5.7% available chlorine.

Richard

Interesting....I just looked on the new jug of Regular Clorox in my laundry room and it, too, says 6% and I also looked at a jug of generic bleach from Ace Hardware and it says 5.25%. I also remember the older jugs of Regular chlorox used to say 5.25%. I wonder if Clorox has bumped up the strength of their bleach a bit so it 'whitens' better? The store I work at sells 'liquid chlorine' in both 10% (HTH brand gallons) and 12.5% (The carbouys we fill from our tank). The 12.5% is supposed to be around 14-16% when delivered, according to the company we get it from, to compensate for the loss of strenth on storage.
The plot seems to thicken the deeper we dig........

[chem geek]

Yes, it does appear that Clorox increased their Regular concentration from 5.25% to 6.0% at some point in time so that 5.25% is now the generic brand concentration.

Additional inconsistencies abound. The chlorine I get from my pool store which comes in gallon plastic jugs labeled Sani-Clor and manufactured by Hasa, says on the bottle that it has 12.5% Sodium Hypochlorite as the active ingredient, but it also says that 3-1/4 quarts added to 10,000 gallons increases chlorine by 10 ppm. This latter calculation only makes sense if 12.5% is a Trade %. The $2.50/gallon price is just for the chlorine. The gallon jugs come 4 to a plastic case and there is a deposit per bottle ($0.50 I think) and case ($1.00 or $2.00 I think), but since I always just exchange one case with 4 bottles for another my effective cost is just the $2.50/gallon plus a tiny amount of interest I'm losing (by not investing) on the $4.00 total deposit.

On the other hand, I found Kem-Tek 10% chlorinating liquid that claims 10% Sodium Hypochlorite and it says that 11 ounces in 10,000 gallons yields 1 ppm which only makes sense if 10% is a Weight % of sodium hypochlorite and even then 12 ounces would be more accurate.

So what's the bottom line? It appears that the manufacturers are not consistent. Combine that with the loss of chlorine over time and this means you can really only know what you are getting by testing it, either through a straight dilution test or by testing your pool before and after a significant addition (waiting an hour). Picky, picky, picky...

Richard

[medvampire]

We use to have to test each lot and shipment of chlorx coming in to the hospital by spec gravity. We used a refractometer and had a chart that would allow us to get a 6000 ppm dilution for sanitizing surfaces. We logged each test and the variances would astound you even with in lot test. The hospital where I work doesn’t test due to the HIV scare is winding down. Like Richard mentioned you may have to test each time.
Steve

[fcfrey]

Since I am now injecting a bleach solution with a pump I test every batch I mix up. Today I over-shot on the pumping rate so I decided to mix a weaker concentration. I put one 182 oz bottle of Clorox with two 182 oz bottles of pool water to make what I would have thought to be a ~2% solution. When I tested it ---- it was 3.2% ---- repeated the FAS-DPD test and got the same thing??????? ??????? I did not test the bleach before I mixed it.

My pool water was 7.3ppm but that's a long way from the 6% ?? bleach that it was mixed with.

[chem geek]

Your 3.2% one-third diluted measurement doesn't make sense, even for Clorox Ultra. I don't know what to say. Perhaps try diluting it directly next time. And you are right that your pool water should have minimal effect on the final measurement since it is has so much lower chlorine level than the 6% bleach.

[fcfrey]

I tested bleach and my injection solution again today and found the Clorox Ultra I bought from Sams is running about 7.2% by FAS-DPD test. What I can't figure is that a 1 to 3 (bleach to water) dilution is still testing at 2.4% solution for my injection pump. Does this compute??? (maybe it's this "new math" )

[chem geek]

I tested bleach and my injection solution again today and found the Clorox Ultra I bought from Sams is running about 7.2% by FAS-DPD test. What I can't figure is that a 1 to 3 (bleach to water) dilution is still testing at 2.4% solution for my injection pump. Does this compute??? (maybe it's this "new math" )

Well 2.4% is a lot closer than the 3.2% you reported earlier. When you say "1 to 3" do you mean 1 volume of bleach in 3 volumes of water or do you mean 1 volume of bleach into 3 total volumes (i.e. 2 volumes of water)? You are right that starting with 7.2% and truly diluting 1 part plus 3 parts water (a 25% dilution) should yield 1.8% and not the 2.4% you are getting. On the other hand, if you were doing 1 part into 3 total (so 1 chlorine and 2 water), then this would be a one-third diultion which should get 2.4% which is exactly what you got. So either there is something really screwy or your 1 to 3 wasn't 1 part bleach and 3 parts water, but was 1 part bleach into 3 total parts (2 parts water).

Perhaps if you explain how you did the 1 to 3 dilution this might clear things up.

Richard