smaller tabs = greater surface area so they dissolve faster if you put the same weight of tabs in the feeder.

As far as quality goes, I always tell my customers they can buy all their chemicals at the discount store if they want, except for pucks. I've found the cheaper pucks dissolve nicely for the first little while then turn to pulp while a quality puck will dissolve evenly until it's gone.

Thanks - I'm thinking of using the 3" pucks because I found that the 1" tabs dissolve too quickly. How can one tell the difference between a quality puck and a cheap one - just based on price?

Chlorine dramatically loses strenght while it sits on the store shelf or in the bucket at your house. For this reason you don't want to buy the large containers for the slighty lower price per lb or the end of season specials. The individually wrapped tabs seem to hold up better but I don't know this for a fact. You definitely want the 99% tabs.

What you are regulating is the amount of water going through the chlorinator. When you turn it down to lower levels you increase the crusting potential of the tubing, flow regulator and all interior componets of the chlorinator. For that reason the larger tabs are better.