Just realized I have a holiday weekend coming up the beginning of Sept so might flood the tank then. Nervous, though, because the transition to submersed is going to be tough. That means I need to order the filters NOW. Trying to decide between an Oase Thermo 600 paired with a Oase Biomaster 600 non-thermal, or a EHEIM 2217 Classic. I only need a heater for Dec through Feb; is it OK to get a Thermo but leave the heater turned off most of the year?