# Max depth of canister outlet?



## Daryl (Jun 1, 2010)

I have an idea for a riverine tank. I need to know if there is a maximum depth I can place a canister filter _outlet_?

I'd like to use spray bar returns and have one near the surface, the other near the substrate (or at half depth). They would be positioned perpendicular to the back of the tank in an effort to recreate the unidirectional flow & current of a stream.

Doable? I have a simple idea for how to DIY build the spray bar but don't know if canister filters are rated to operate at a maximum depth? I know they have head ratings; is there a way to calculate how much each 6 inches of water column above the outlet adds to the effective "head height"?


----------



## charles (Apr 21, 2010)

I would just use a circulation powerhead instead.


----------



## Daryl (Jun 1, 2010)

I'm a minimalist - I don't want any extra equipment in the tank. I don't even like having heaters in the tank.

I'm thinking it's not going to be an issue - I mean there are guys running under-gravel jets from the pumps in their sump... In that scenario the only issue is making sure you have a syphon break in the event there is a power failure.

But the way I see it, with a closed loop system like a canister, if it's going to leak it will drain water all the way down to the level of the filter intakes - which are often recommended by the manufacturer to be about 4" above the substrate. So if it leaks I'm getting flooded out regardless.


----------



## mikebike (Sep 8, 2010)

On my 90 gallon tank using an FX5 on the floor I ran the return to the bottom of the tank then 90 degrees to create a bottom length flow to the inlet at the opposite bottom corner.
the surface of the water was at 48" off the floor.
It had good flow and force


----------



## Daryl (Jun 1, 2010)

That's good to know. I'm assuming the prime factor is going to be "effective head height". 

Did you have to DIY your return?


----------



## mikebike (Sep 8, 2010)

No I just put a 90 on the end of it one inch above the bottom to create a current that swept the bottom front edge of the 48 inch long tank.

the bottom of the tank as about 32 inches off the floor so the efective head is about 34 inches


----------



## charles (Apr 21, 2010)

but you will never get a small circulation powerhead can put out. A FX5 supposing do 500gph+. A medium size 3 hydor can do 825 gph. A filter is good to do what is best it is doing, which is filtering out your water. It can be used as a surface breakage for promoting gas exchange, but I don't think it can produce enough current. If you want just that little bit, I guess it is ok.


----------



## tony1928 (Apr 22, 2010)

Yup, agree with Charles. You will never get the flow you need to try to replicate a riverine environment with just a canister return. On my 8 foot tank, I run a Tunze 6125 which runs at over 3000gph and produces a fairly wide dispersed flow. As big as that sounds, it does not produce what I would imagine the amount of flow that a river would feel like. The flow is rather gentle.


----------

