I have a 30 gal planted aquarium with natural gravel & a w/d & heater. I am setting up a 150 gal tank. And I am thinking about a Kitty litter / sand substrate I am also thinking of adding heat to the substrate, if so should I go with under tank or in the substrate? Or staying with the same setup as my 30g . Any help on which way I should go? TIA Steve smartin at nmia_com