i was told that shocking with MPS will result in TDS acumulating faster than with a chlorine shock. Some folks use a super does of chlorine to shock. I have heard of others alternating between MPS and Chlorine.
Over the years, I have shocked both ways. I prefer MPS. I believe it does a more complete job and I don't have to give up the spa for a day waiting for the chlorine levels to come down. TDS has never been a concern for me.
Because I use a minimal amount of dichlor after use, I like to raise my free chlorine level to 5 ppm once per week. That generally means about one tablespn for my 485 gallons. At that level, I can still use the spa and I get a good spike in sanitation.
