Heaters in HOB Filters

[AJ_77]

Adjust the flow to minimum, fill the chamber with LR and/or sponge blocks etc, and it doesn't cause too much havoc. I like the way some people light their 500s and use them for a refugium of sorts.

My 300 has only a thermometer in there, but a small Visitherm would fit. I put the foam around it, and some rubble rocks behind...