My understanding is that when the chemical pucks get wet, they put off varying degrees of heat and gasses, and the reason you can't put cal=hypo in a feeder that's not designed for it is that the trichlor feeders aren't equipped to handle the heat and pressure buildup of dissolving cal-hypo. So the short answer to your question is, no, don't put cal-hypo pucks in a feeder unless it's specifically designed for cal-hypo.

Janet