You want to think about redundancy too - both ends. I have a 250L system with a 300W main heater and 200W backup. The main is controlled by my Apex controller, set to turn on < 25 and off > 25.2 degrees celsius. The main heater’s thermostat is set to about 26 degrees C so if the Apex malfunctioned and left the heater on, it will turn off before the water gets too hot.
The backup heater is not controlled by my Apex and is set to ~24.5 degrees C. If the main heater fails, or if the Apex malfunctions and doesn’t turn it on, the backup will kick in to ensure the water doesn’t get too cold.
The only other maintenance I need to do is periodically check the backup is still working. That typically happens when I do a water change as the water going into the sump is a little colder and I see the backup kick in as well as the main.
The backup heater is not controlled by my Apex and is set to ~24.5 degrees C. If the main heater fails, or if the Apex malfunctions and doesn’t turn it on, the backup will kick in to ensure the water doesn’t get too cold.
The only other maintenance I need to do is periodically check the backup is still working. That typically happens when I do a water change as the water going into the sump is a little colder and I see the backup kick in as well as the main.
