Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I do not keep my Q-tanks running.
Keep a little spare media in a running tank, keep the empty Q-tanks in storage, and set them up when needed. I do have some running as plant-only tanks, and no heater. I could call those Q-tanks, I suppose.
Anyway, lower temperature is a good way to keep the bacteria alive, but living on a slower level. They must not be frozen, but cool temps are fine. Just keep on feeding the tanks ammonia to keep them alive. Feed less when the temperature goes down.