Thanks Richard,

Everything thing you said makes sense. I have used liquid chlorine exclusively since the pool was built, but since I also have a salt system for producing chlorine (which or course can't keep up with demand), the tri-chlor pucks in combination with liquid chlorine seemed like an economic way to both lower pH (to compensate for the liquid chlorine's pH increase) and to add CYA required by the salt system (for some unknown reason I lose 40-50% of my CYA during the winter). Purchasing acid and CYA separately is becoming increasingly expensive.

I also have a leaf trap system that collects leaves in a basket in a cavity similar to the skimmer only much deeper; water flows from the pump and pool (using the "venturi" principle) through this cavity directly into the pool and has no metal parts, so I was thinking this would be an excellent alternative to the skimmer, but in your reply you mentioned the area around the skimmer can also be damaged, so maybe that won't work either. Plus you have a theory of the low acidity diffusing into the pipes, possibly back to the heater/pump.

If your theory about the diffusion is correct, then wouldn't in-line chlorinators using these pucks have similar issues? Especially since they are typically even close to the equipment?

Thanks, David