I have a breand new Arctic ocean swim spa & while I'm happy with it so far, I am not happy with how much $ it may cost me to keep it balanced. I have the saltwater/ozone option but I've been told to shock it after every use (which is daily for one person). Since it is 1600 gallons, it needs 10-14 oz each day, which is about $4/day or $120/mo, which I wasn't counting on. That's the price from my dealer's brand (Apollo) and all it says on the bottle is "contains Potassium Monopersulfate". I've found better deals elsewhere, but I can't tell if they have the same formula. One says 43% PPMS...does anyone know if that will work? Appreciate any guidance...1st time spa owner.