Power outtage - Backflow

[TetraBotia]

backflow valve is another name, methinks.

I have seen that as well, but "Check Valve" was what I was looking for.

I think they do pose some kind of resistance on normal flow volume, but it is fairly negligable.

I think some use swing gates, and some use ball valves. I would look for those that use swing valves, or ball gates, or gate valves, or ball swings...

Hey! Wait a minute... forget the ball swings and ball gates...

sounds painfull...

I would recommend ball type, where you are dealing with a system that would allow algae (yes, it grows even where there is no light) and sludge/slime buildup. Ball types vibrate and "roll" and bounce around, creating contact movement that will help keep the buildup down. Gates open, and stay in one place until closing, and buildup might not be prevented. That means, when they have to close, the cleaner of the two will be more likely to close securely.

Ball Type.

Hopefully you can find a quiet one.

 

[RTR]

Check valves fail. Relying on such for power off situations is an ineffective bandaid.

A canister filter is a sealed operation other than the intake and output. If it leaks in power off, it has a defective seal or is cracked somewhere. The suggestions to observe the unit are good. See where the leak originates and replce the associated seal.

 

[anonapersona]

Bad seals

Bad seals or too much distance from canister to tank water level.

When the filter is off, the canister and its seals are subjected to the highest pressure, due to the height from the filter to the tank water level. This is why there is a max distance noted for canisters, see the instructions. When the unit is running, there is less pressure inside the canister as the impeller is pushing that column of water up and holds some of that weight, so to speak.

The main seal is the likely problem, but it could be any other seal as well, check all hose connections.