Using a canister filter and an overflow for a sump?

Ruben,

As George pointed out, although it would work, the cannister filter is
not really designed to do that kind of work (moving water from one
level to another, especially with the height I think you're talking
about.) I would hate to hear of your pump burning up from excess
backpressure caused by the height differential and the filtration
combined (though some would argue this point since most cannister
filters use magnetic drive impellers and are thereby non positive
displacement pumps). Generally speaking, the cannister filter is
designed as a sealed system to return water to the same height that the
syphon draws from. As such, the pump is designed only to deal with the
back pressure of any build up in the filter media. That being said, if
you did set up the cannister to draw from the sump and return to the
tank (assuming that the sump is in the stand, or a good 4 feet
different in water levels), the decrease in the water flow could cause
anaerobic conditions in the filter as well as working the pump harder
than it was designed to. To get the maximum effect from the cannister
filter you should have it draw and return from the same water. But,
you can have it draw from and return to the sump. In this design it
would not act as much as a physical but more as a biological filter
(assuming that your over flow has a prefilter on it). Long story
short, I would buy a return pump designed to do what you're looking
for; lift water. As long as you're not returning to the tank faster
than your overflow box can handle, the water will balance out. If you
have questions on how to set the water height in the sump or tank so
that power failure will not cause a flood, let me know. Also, do you
have a system in place to keep the syphon from breaking in your
overflow box? (This can burn a return pump as well)... Best of luck...
Russ



George Patterson wrote:
RubenD wrote:

What do you think the drawbacks are if there's any?

Well, if I understand you correctly, you're going to have a 10 gallon tank on
the floor, the cannister syphon will be in the 10 gallon, and the cannister will
be pumping water up to the main tank. Cannister filters aren't really designed
to act as a pump, so I would check with the manufacturer to see how high a water
column yours can handle (in other words, how different can the height of the
intake and discharge tubes be).

Also keep in mind that the cannister filter will serve as a great syphon to pull
water out of your main tank if the power should fail. Make sure the discharge
tube is high enough in the main tank to prevent a disaster.

George Patterson
All successes in conservation are temporary. All defeats are permanent.