Can this work with a fluval FX5?

[GuOD]

Hi everyone,

I have a Fluval FX5 which I've discovered is pretty useless for my SW tank but I want to make use of it still.

I was thinking of trying to set up a refugium that's about 30g or so and using my Fluval to pump it. I wasn't sure if it's too much flow or not though.

Planned setup:
Tank overflow to 30g aquarium on floor --> fluval intake in 30g--> fluval output into main tank.

The fluval flow rate is about 900gph... so I don't know if this intake is too strong for the 30g tank or not.

Does anyone have any opinions?

[Zagz]

I'm a freshie so can't speak from personal experience with refugiums. But if the intake is in the 30 gal and the output into the main tank, I would think it would be ok. Any idea how fast the water would flow from the main tank to the refugium? As I said I've never worked with a refugium, but I have a FX5. As long as the overflow from the main tank would remain constant and keep up you should be fine. You could set it up and test it I suppose and if it didn't work dismantle it again. A bit of work but not too much I would think to see if it works.

[tropicalfish]

it would work. you could keep the FX5 chamber empty, and have it running and put your heater inside the FX5 or something. Also, MAKE SURE that your overflow keeps up with the high water flow. If it does not, your 30 gallons of water in the refugium will come out and make a mess.

[GuOD]

I'd probably just stick my heaters and protein skimmer on the refugium tank. It's not even a refugium per se, simply a tank of water on the ground that would make water changes a heck of a lot easier

So the only concern really is having an overflow siphon that can keep up with the Fluval FX5 flowrate? I have no idea how they work so I'll have to investigate. Unfortunately, I think the FX5 can only go at full power

[squawkbert]

Try it - you can pull the trays and toss some nylon pot scrubbers in there - more biomedia, modest flow hit.

[Zagz]

The FX5 can have the flow adjusted on the tubes that go into the cannister. Whether this would make a huge difference I don't know. The cannister flows slower full of media rather than empty.

[GuOD]

Originally Posted by Zagz

The FX5 can have the flow adjusted on the tubes that go into the cannister. Whether this would make a huge difference I don't know. The cannister flows slower full of media rather than empty.

Are you suggesting half-closing the locking valves?

And it definitley pumps slower full of media... it's just that I don't want to create a nitrate factory

[Zagz]

Yes half closing the locking valve slows the flow. I'm not sure it would do enough to make a significant difference though. I'll be interested in how you make out. I'm sure it will work providing the overflow can flow fast enough.

[Lonewolfblue]

Also, how would you prime the system if the intake is at the same level or barely under the refugium and the output in the main tank well above the canister level? And what protection would you have in place so that if the power went out, that you wouldn't get a back-siphon from the tank back to the refugium, and cause it to overflow?

[Zagz]

The FX5 is self priming, you can start the motor for a minute and the cannister primes itself.
The power issue is a very good point.

[tropicalfish]

Since it is an overflow, more water will not come out if the water line is below the overflow setting. So, no water will come out.....,...
that is depending on your setup...

[Lonewolfblue]

Well, if you have the intake in the 30G and the output in the main tank, it has nothing to do with the overflow. The overflow is just for the water going from the main tank back to the refugium. So if the power were cut off, the water in the canister would create a back siphon until there is a break in the output tube in the tank. That means that the water in the main tank will drain off to the point where the output is. Now if the output was above the waterline, that wouldn't be a problem then.

[tropicalfish]

Ohhhhhhhhhhh
I see what you mean...

[andywg]

Also, I would worry about the flow rate. External cannisters don't really deal with head as they are taking water from the same height as they are returning it and thus hitting a near equilibrium. I do not think the same flow rate would be achieved when pumping from a lower area to a higher one.

Also, as mentioned you would have to worry about back-syphon when the power is out. And while the FX5 is supposed to automatically set up the syphon, that is usually with the water coming in from at least a few feet higher. I doubt it is designed to work with water at a similar level.

You would be better off using a proper return pump and saving the FX5 for flow rate, or even create a non lit fuge in the FX5. Fill it with LR rubble (and any chemical media you want to run) and you should still get some benefit from it.