400 Gallon Canister Filter for 40 Gallon Tank?

[trombonier]

If I have a 400 Gallon Canister Filter would I be able to use it safely in my 40 Gallon Mbuna Tank?

 

[SherLar]

Mbunas typically don't like a lot of water flow.
Does the filter have a flow rate control? If so, you could just turn it down. If not, try to position your output so that the flow is disrupted by decor like stones, or against the glass; anything to slow down the water movement, and it may work OK. No such thing as too much filtration.