just wanted to ask if anyone using 3% hydrogen peroxide to remove chlorine from your strike/sparge water? If yes how many ml/l or gallon? Thank you.

  • Ingredients and quantity Contains 2.5 to 3.5 w / v% of hydrogen peroxide (H2O2). Contains ethanol and phenacetin as additives. Translated from Japanese – Iacovlev Jan 15 '20 at 22:06
  • While it's possible to do this, don't most people just use Potassium Metabisulfite? – farmersteve Jan 17 '20 at 19:51

Congratulations, you made me pull out my ancient chemistry knowledge and periodic table data. (I'm a chemical engineer by degree, but that was more than 20 years ago. Hope I still know what the heck I'm doing!)

Based on molecular weights and the fact that sodium hypochlorite reacts with hydrogen peroxide thusly:

NaOCl + H2O2 --> HCl + H2O + O2

It appears that you would need 34/74.5 = 45.6% as much hydrogen peroxide as the chlorinated water, assuming both are at a concentration of 3%. But I doubt water contains 3% sodium hypochlorite. Looking that up... it appears that a common municipal water system actually doses the sodium hypochlorite not at 3% but rather about 0.5%. So that is 1/6 as much as I thought. So that's 45.6/6 = 7.6% as much hydrogen peroxide you will need to neutralize the hypochlorite compared to the volume of chlorinated water. Or volumetrically that's 76 ml per liter of water, or would be about 10 ounces per gallon.

Kind of a lot in my opinion. But I understand the reaction is very fast, virtually instantaneous. You might even see oxygen visibly bubbling out upon mixing (I haven't tried it). Don't have any open flames nearby, just in case. But it should definitely work.

Hope I'm right. Interesting idea. Thanks for the question! I might have to give this a try sometime.

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    Note: This should also acidify the water significantly, from a pH that might start close to 8, down to a pH in the 6's, because the alkaline nature of the hypochlorite will basically be converted into hydrochloric acid when the oxygen all goes up & out. Interesting stuff. – dmtaylor Jan 15 '20 at 5:37
  • Thank you for answer the question in detail, it could be better solution then camden tables and bid time saver if you need to boil brewing water, but 76 ml per liter a little scares me. I will give it a go anyway I think. – Iacovlev Jan 15 '20 at 5:44
  • Thank you for your help, take your time:-) Will be huge time saver if it work out . Thanx. – Iacovlev Jan 15 '20 at 6:00
  • Second-guessed myself and double-checked my math... but yeah, I'm even more certain that these numbers are correct. 76 ml of hydrogen peroxide contains 2.28 grams of H2O2, which will react with perfect stoichiometry when added to a liter of water containing 5 grams sodium hypochlorite, giving out a little more HCl acid, and a little less (2.146 grams(! like you're going to weigh it!)) of oxygen gas. Cool. – dmtaylor Jan 15 '20 at 6:05
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    Cool answer and good use of chemistry. I'd just add that I'd be concerned about other stuff in the peroxide bottle affecting the flavor of the beer as well. I don't know if there are stabilizers or other chemicals that make up the other 97% of the bottle. H202 isn't hugely stable on its own so there must be more than just water in that 97%. Just something to think about. – brewchez Jan 15 '20 at 13:20

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