I haven't seen Monopersulfate/MPS (short chemical name) in a slow dissolve form. I don't use it except when converting from Baquacil and like products to chlorine sanitation.

Just prior to winterizing, I normally add several gallons of bleach to boost the chlorine and some algaecide, then winterize it.

There is no magic. Keep light out and it opens as it was closed. Expensive additives, IMHO, are just a waste of your money. If you want to spend it, thanks for helping the economy.

Scott