Canister does not fill completely when priming.

by Krystle
(Sherwood Park, AB, CAN)

I have read on this site several times that you should always start your filters from empty before priming them.

I have to admit that I have been starting with full canisters, because when I try to start from empty the canisters do not fill all the way.

What causes the canisters to not fill completely when primed from empty? What damage do you do to your filters by starting with full canisters?

Is this also the reason why the water level drops in my filters once they are running to a couple of inches below the top of the canister?


thanks.

A: You have an air leak someplace on the intake side. This problem is masked by trying to "help" the priming processs by pre-filling the canisters. I urge you to look a the setup video provided by Mars Fishcare. This will refresh your memory on how to setup and maintain a filter for best results.

The main problem in pre-filling the canister is that the water never gets enough momentum going to push up into the rotor-impeller area. Then if you have a small leak in the intake side or the water level is never high enough to fill the rotor/impeller area (the volute in pump speak) then you will always be pumping water mixed with air. This is called cavitation or a pump is "cavitating". This will wear out your rotors faster and cause the motor to run hot. I also urge you to view the short videos at PlanetRena Direct especially on the rotor/impeller.