Merge 2 return pumps into one outlet

[James77]

This is for a planted tank. I have 2 Eheim canister filters. Rather than use the provided tubes to return the water, I would rather them both merge into one outlet, which will be a hole drilled into the tank with a bulkhead.

Will anything negative result from what is pictured below? The output from each will be very similar. I imagine there will be some type of head loss, I am just wondering if it would be significant.

 

[Mrramsey]

You would want to get a wye. The key here though is if the lines coming off of the canisters are 1/2" each then the other line needs to be larger, like 1".

 

[RocketEngineer]

It doesn't work because the pumps are fighting against each other. You would get the most flow out of each filter having its own return to the tank.

 

[Mrramsey]

I wouldn't say it doesn't work but yes it certainly wouldn't perform as well as the two individually.

 

[Mrramsey]

Actually just though of a possible negative. What happens if one fails? You might end up with a backward flow causing the nasties in the filter to back up into the tank.

 

[ca1ore]

I ran two pumps this way for a while, and while it is not ideal (better either to have a single, bigger pump or two returns) because I'm not sure that it was fully additive, it can be made to work. Key is to step up the pipe size post the merge point. I actually ran both my pumps with a ball-style check valve in the event one of hem should fail. Though this adds friction head - again robbing you of flow.

 

[karimwassef]

Pumps don't parallel without one way valves. Each pump will now be forcing water up to the DT and also back down into the outlet of the other pump. You won't notice the loss without measuring the flow, but it's very real.

The loss of efficiency makes this wasteful (lots of electricity for a lot less flow).

Use separate returns, one way valves (not recommeded), or connect them as far away from each other's outlets as possible so that the path for back flow is very long = high impedance.

It'll look like it's working, but measure the flow to power usage to see the impact.

 

[James77]

Thanks everyone.

The GPH returning from the Eheim canisters is already pushing it as far as being enough flow. I may explore just using a sump on the planted tank....basically making the sump a somewhat sealed canister.

 

[Mrramsey]

Thanks everyone.

The GPH returning from the Eheim canisters is already pushing it as far as being enough flow. I may explore just using a sump on the planted tank....basically making the sump a somewhat sealed canister.

I ran a sump when I had my planted tank. Drains spilled through a filter pad then through a drip plate over 3 gallons of bio balls. Flowed through a medium sponge. Then an equipment chamber for the heater. Through a bubble trap and into the return chamber. Worked really well. Changed the filter pad once a month.