Your're not really supposed to put the trichlor pucks in the skimmer. My understanding is that triclor in the sticks (slow sticks) are bound is such a way that they will dissolve when water is flowing around them. The pucks will dissolve withthe water flowing past them or not. Therefore, if you drop the pucks in the skimmer, the chlorine will constantly leach out without the pump running and somehow affect (rot) the pvc piping connecting your skimmer box. The sticks should only dissolve with the pump running, thereby keeping the local concentration of chlorine in the skimmer piping to a minimum.

That's the theory anyway.

That bieng said, I remember my parents using pucks exclusively in our pool skimmer for years when growing up.

I switched to bleach last year. I was more worried about excessive CYA levels when using pucks.

Hope this helps.

-LA