I started using bleach about 2 years ago when CYA was too high. It is my opinion that most pool owners use pucks because it is just the mentality of pool owners and most pool service people. Is this a correct asessment? I suppose it really does not matter but I would guess that strictly bleach users would be a small minority ( probably less than 5% of all pool owners)of the santizing methods used. In fact, I know many people that have pools and I am the only one who pours cloxox bleach into their pool. I am glad I found this site a few years ago, but I have lugged a lot of gallons jugs to my pool. Most people are just too lazy for this kind of work and pucks seem to be an easy way out. Just an observation.