I used PMPS last year. 2 bags each sunday for my 22,200 gallon pool.

It worked great. Bought it before I found this place.

Looking at the $ this year, it will cost me $9.50 to shock with 6% liquid bleach (cheapest I can buy locally) or $5 with PMPS.

As long as I keep the FC up with the bleach, PMPS seems to work well.