seen alot of talk about fog but i think i have the solutiion to the problem with heat from ultrasonic foggers without using a separate res., Use a setup similar to a fogbox with a few small tweaks. Drip feed, do away with the pump sprays and house your fogger in a insulated bowl which takes a bit of adjust ment but have hole in the side of the bowl to allow fogger to stay at right depth and allow water to enter fogger bowl without heating the whole tank..Worked for the last 2yrs no cooler no problem actually needs heat in res tank in winter , which starts now