Head height flow reduction

  • We are currently upgrading MFK. thanks! -neo
C

CJB

Feeder Fish
MFK Member
Dec 20, 2008
113
1
0
California
I have been reading around, and from the looks of it, the higher the head height, the less gph you get from your filter.

So my question is this. I have a Fluval 404 on a 55gal tank. The filter is about 3-3.5ft below my tank. Am I losing a lot of gph from my canister having to push the water that high? :screwy:
 
What's important is if it is doing the job. I doubt Fluval is going to have performance curves for it since it is not customizable. Search their site to find out. Anyway, you can expect 30-50% reduction in flow (not that you can do anything to change it).

Don't freak about the head loss. Canisters are pretty much 'plug and play'. You match the gallonage on the box to your tank and you are good to go. They already did the math and took into consideration the average stand and tank height.
 
You guys are missing a very crucial point... canisters are an enclosed system...

What happens when you turn the canister off... it stops... Nothing more... now lift the return line up... what happens... the water in the hose balances at the surface of the tank's water... Do that same thing on a sump pump and what happens... the line empties and the water balances at the surface of the sump, not the tank...

Since the canister is an enclosed system, its point of equilibrium is the surface of the tank... just like a siphon hose... ;)

And no, canister filter manufacturers do not include head pressure into their flow rates; the vast majority don’t even take media into account...

;)
 
^ Yep, that's right. I totally missed the obvious. Being a "closed loop" means that there is no vertical head loss. What is "lost" going up is countered by the gain going down. The two cancel each other out.
 
Ah, okay I see.

Thanks guys!
 
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