Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
The tanks with no heater, filter, light or whatever may be OK, as long as the livestock are OK with the room conditions. If the power goes out can you maintain the room as warm as they need?
A small tank, with filter etc. and overstocked would be in trouble if the power went out.
A large % of the filtration is the plants, and they only do their thing when the light is on.
Filter (any water movement- power head, filter, air bubbler) is required to keep the O2 level high for the fish and bacteria. Again, plants won't do this when the light is off.
So, I can say, yes, the guidelines for stocking levels and equipment can be different, but the most basic rule of all still needs to be:
Set up the tank and be prepared for the 'worst case' scenario.