DIY Canister Filter - Pressure?

[JamieOxford]

So I started building a canister filter a few weeks back and I fianlly finished it today. It works well at pumping out the water, clearing 250 ml in around 10 seconds.

My issue is that the pump isn't sucking the water back in through the other tube. I used this article here for inspiration.

http://www.petfrd.com/forum/articles...rtid=87&page=3

I adapted it slightly to include two canister to make it easier to remove and also to give me more space for filtration and bacteria to grow.

Here are some pictures of the setup at present:






Help would be appreciated and I just want to get it up and running so I can start planting and cycling!

[Landau]

If water is going out and none coming in, my guess is you have a leak and air is getting being sucked in.

I'd double and triple check all your seals.

[JamieOxford]

I've had a look and re-sealed them but no luck. I might buy a few new bits of better quality tupperware and have a go at redoing it if it doesn't work this time.

[VincentK]

Is the pump supposed to be inside the tank?

[JamieOxford]

No, it's meant to be outside the tank, inside the filter.
I bought a "water feature" pump which is meant to suck the water up through the bottom and fire it out the top (giving me plenty of pressure)

Here's a diagram of what I'm trying to achieve.

[VincentK]

Maybe it's the pump that's not strong enough? Are both the canisters filled with water before you turn on the pump?

[JamieOxford]

Yeah I filled them both before hand. The thing is the canister on the left (with the pump in) pumps out most of the water inside the left canister within around 10 seconds but it isn't sucking any water through. I guess it's just a seal issue. Gonna go get another canister now and get working on fixing the problem! Will keep you posted on my progress. Thanks for the help!

[Craigthor]

You have to get all the air from the lines. Cannisters are gravity fed and will not start the siphon themselves.

Craig

[Hoppy]

The third photo seems to show that the clear plastic tube from the tank is kinked a bit, which may be restricting the inlet flow. That shouldn't cause air to show up in either of the canisters, but it would increase the vacuum in those canisters, so any leak would be worse.

[JamieOxford]

The third picture shows a clear tube - it's acrylic and bent round. There's no kinks. I'm just gonna get another bit of tupperware and re do all the seals again.

[heydude819]

where exactly is the placement of the tupperware in relation to your tank's waterline? I made my own canister filters back then using the lock-n-lock containers (get them for about $4 at walmart).

At first the canisters were near the top of the tank waterline and there wasn't much flow...the canisters would push water out faster than it can suck, so it caused the tupperware to contract. After i lowered the placement of the tupperware the issue disappeared.

fyi, it's a pain to service the tupperware. The silicone would loosen each time the tubings move, and eventually you would need to reseal it. In the end i got a xp3 and life was great.

[JamieOxford]

The canisters are around the same height as the tank. I'll get some more tubing tomorrow and lower them.

I used Araldite (epoxy resin) rather than silicon for the seals so it's a lot tougher. I tried it with silicon but it was pretty useless because there is little surface area between the two contact points.

Will the pump still be powerful enough to push the water back up into the tank do you reckon?

[Hoppy]

The pump doesn't have to work any harder with the canister being below the tank than if it is even with the tank. The head the pump sees is from flow friction and the height of the return tube over the water line - a few inches. This is because both the pump inlet and outlet are at the same distance below the water, so both have the same static head pressure.

[JamieOxford]

So I finally got it all set up. Had it running for a few days and the impeller broke and is now fused with the internal part of the pump somehow. One of the seals also burst too! Fun fun fun...

That's enough with this. I'm gonna stick with what I know - an internal Fluval filter.

Which do you recommend for my tank? A U1 or U2 filter? Obviously the U1 is meant for smaller tanks, but it lacks the carbon and bio-media of the U2.
Then again, I don't know about the U2 because it's a higher output filter and I don't want it to be disturbing my plants. However the tank is two foot long.
Advice please?

[VincentK]

Get the U2 and take out the carbon and replace will filter floss and have it facing so it shoots along the two feet.