12.5% percentages

Hey guys! I just wanted to check my math and make sure I am correct. I will be using 12.5 %SH. If I want a 3% mixture would it be 12 GAL of SH and 38 GAL of water. Of course I will be adding the surfactant. Also I will be using a 50 gal tank. Thanks in advance!!

12 gallons of 12.5% SH
37.5 Gallons of Water
0.5 gallons of surfactant


115 pounds of 12.5% SH
312.5 pounds of water
4.2 pounds of surfactant

= 431.7 pounds.

only 12.5% of your SH is active, so that is 14.375 pounds of SH

14.375 pounds of SH is 3.33% active SH in the 431.7 pounds.

Anyone want to check my math???

when you add your surfactant, do you add it to the final or make it equal the remaining water?

Want to really throw people off, start explaining how 10% sh is the exact same as 12.5%, it’s just whether the manufacturer measures by volume or by weight as to how they label the percentage. About the same way that small aircraft pilots buy fuel by the gallon, but measure it in lbs, because temps can change how much energy you can get out of a gallon of fuel, but how much you get from a pound of fuel stays constant. Folks who work at water treatment facilities can probably explain it best, as they deal with both measurements.

Have you ever tasted 10% SH compared to 12.5. The taste is way different, no way it’s the same.


It is the same. Seriously, ask someone who works at a water treatment facility who buys from several suppliers. How many ounces is 10% of a gallon…sh will never “taste” the same between fill-ups unless you get it straight from the manufacturer, the same batch, the same day. Way, way too many variables to go on taste or smell. Call univar, or someone similar, and ask them the difference. They can explain it better than I can.

I believe it’s based off whether they measure in sodium hypochlorite vs available chlorine. The available chlorine in 12.5% sodium hypochlorite is 10.4%

This all comes down to units of measure. that is why in my explanation I converted it to pounds. 12.5% by volume vs. by weight are different animals.

As my old chemistry teacher use to say “Your units of measure are vitally important. Pay attention to them or one day you will find yourself trying to calculate how much a mile weighs”

That one stuck with me!

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Mac, are you downstreaming it? If so your 3% will be about .3% hitting the surface. That’s likely way too low. If you are directly applying via pump up sprayer or other means, never mind! :slightly_smiling_face:

So at a pool store is 10% the same as 12.5%?

That was sarcasm…don’t drink bleach lol


Unless you wash parking garages! :grin:

No I will be using a dedicated pump. I understand the downstream rates. But just making sure of the other. The 3 % I was talking about was for instance on doing roofs or such.

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Never know these days lol! I mean, people do eat Tide pods and drive cars while doing the bird box challenge…


It all depends on the manufacturer.

got a call going to have to do a small commercial job soon :rage: .

Called pool store, SH is from October. How bad is the 12.5% gonna be? Said they will charge half price, so atleast that is nice.

Not happy, but guy gives me everything except dumpster pads so cant tel him to wait til spring.

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It’s super easy to tell. 12.5% has an oaky finish and 10 is more floral. Make sure to rinse your pallet before trying oxalic.


It won’t be too bad, it hasn’t been hot and it’s been out of the sun. My guess would be above 9%

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6% is sort of a fruity, nutty blend. The box is best lol

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Should be close to 6% now. That’s where it starts to stabilize.