Dupont Oxone Vs. Seaklear Mps

[mcw53]

This is probably a question for chem geek. Comparing the components of Dupont Oxone and SeaKlear's MPS, I noticed that the additional Potassium Peroxymonosulfate comes at expense of Magnesium Carbonate. Question: What is the purpose of magnesium carbonate in an MPS compound? Does it affect (raise) pH/TA or is it used primarily for it's hygroscopic properties?

[chem geek]

Mike,

Sorry I didn't answer this earlier (I must have missed it).

The purpose of the magnesium carbonate (or any form of carbonate including sodium carbonate) is primarily to raise the pH, that is to compensate for the drop in pH at least a little. It also increases TA more than a pure base, due to the addition of carbonate. If there were no added carbonate, then one pound of non-chlorine shock like SeaKlear in 10,000 gallons would lower the pH (including the drop in pH when it oxidizes something) the same as about 7 fluid ounces of Muriatic Acid (31.45% Hydrochloric Acid). However, with 2% magnesium carbonate, it only reduces the pH drop to be equivalent to around 6 fluid ounces of acid so not that much different. If a non-chlorine shock were to be close to pH neutral including the drop in pH when it oxidizes something, then it would need nearly a third of its weight to be magnesium carbonate. To be pH neutral just upon addition, ignoring what would later happen when it oxidized something, it would need around 10% of the weight to be magnesium carbonate.

Richard

[mcw53]

Thanks Richard. Guess that explains why the pH balanced MPS compounds (e.g. Leisure Time's Renew) contain only 32-36% potassium peroxymonosulfate.