Suitable canister for two tanks.

[TheAlpha]

Hi. I intend to use a canister filter to support two 2ft x 1.5ft x 1.5ft tanks.
Can l know which canister should l get and what is the recommended flowrate?

[Shadow]

fish only tank or planted tank?

for Planted tank I would go for either Eheim 2215 or 2217

[vinz]

One canister filter to support two tanks? How are you planning to place the input (to filter) and output?

Recommended flow rate for planted is about 3 times the water volume (total for two tanks) per hour. Get a filter that is slightly higher flow rate as filter media, clogging and normal wear and tear will reduce flow rate over time.

[Shadow]

Hm... I though I filter each

if you want to use 1 filter for 2 tank, you need overflow system and one of your tank must be located under the other tank

[TheAlpha]

One canister filter to support two tanks? How are you planning to place the input (to filter) and output?

Recommended flow rate for planted is about 3 times the water volume (total for two tanks) per hour. Get a filter that is slightly higher flow rate as filter media, clogging and normal wear and tear will reduce flow rate over time.

Hm... I though I filter each

if you want to use 1 filter for 2 tank, you need overflow system and one of your tank must be located under the other tank

I intend to put the output for the top tier's tank and input for the bottom tier's tank.
Yes, l'm thinking about an overflow system as well. I've a simple idea in mind, but it would probably spoil the overall looks of the tank set.

[vinz]

You might have a problem. I believe the canister filter is designed with the assumption that the input and the output is not very different in height... and when the filter is off, the downward force of water in the hoses will find a balance. The impeller will have less problem moving the water.

The way you plan to set up, if the filter is off, the water in the outlet hose (higher) will be exerting a stronger downward force (due to gravity) than the water in the inlet hose (lower). The filter flow rate I believe will be lowered as it is harder to push the water up the outlet hose in this situation.

I know the Eheim Ecco series has a check valve to prevent water back flow, but I'm not sure if that is present in all canister filters. I believe a well designed canister filter should have, but if there is not, and your outlet is submerged, you might find water flowing backwards when your filter is off.

You will find that sumps use much more powerful pumps.

In this case, you can still use canister filter, but:
1. You need a more powerful one than the recommended 3x tank volumes/hr.
2. Make sure the filter has a back flow check valve, or install one in the outlet hose, or make sure the outlet is not submerged (even then, the water in the hose will back flow and push some dirt from the filter out of the inlet hose).

My speculations above are based on my JC physics, and not on actual experience, so you'll need to find out more. I believe my theory is correct, but the severity that it affects your set up, I'm not sure.

[Shadow]

I know the Eheim Ecco series has a check valve to prevent water back flow, but I'm not sure if that is present in all canister filters. I believe a well designed canister filter should have, but if there is not, and your outlet is submerged, you might find water flowing backwards when your filter is off.

Never think of that, scary, especially if power trip or power black out

There is spec in Eheim filter called "Del. head approx Hmax". It will tell you the maximum height that the pump can push but I have no clue what the impact of inlet lower than the outlet . The pump need to do extra work to compensate the different.

[leonard6july]

I got the same set up with a Hailea 28A chiller. I use a 2026 and have the filter outlet a inch below the water surface in case of black out and backflow. So far so good.

[BFG]

Check valve may not work if the siphon flow rate is slow as I've experienced before. What you really need to do is to drill a small anti-siphon hole somewhere near the output tube, a few millimeter below the water surface. If the filter stops, the anti-siphon hole will allow air into the output tube to cancel the siphon effect.

[TheAlpha]

Thanks for the inputs guys!
I'm trying to minimize the number of plugs that I can use because I'm having a 3 tier set-up.
Because l have to consider about lighting and etcs' plug as well.

Hope l can get more valuable advice from this thread. :/