CATDOLL : CATDOLL: What equipment in a tropical fish tank needs to be kept open 24 hours a day?

Filter oxygen pump heater (if it's cold) Buy a better heater that will automatically stop when the temperature reaches a certain level. Neither the filter nor the oxygen pump consumes much power. Look at how many watts these things are. 1° electricity = 1000W. You can divide 1000 by (filter or oxygen pump) to get the number of hours it takes to consume 1° electricity.

The constant temperature rod must be turned on 24 hours a day, and the filtering and oxygenating devices can be purchased with a timer to control the timed operation.

Heating rod and oxygen pump