# Return pump question



## ruckuss (Jan 11, 2015)

Hello, 

If I get a DC return pump to control the flow, can I get away without using a valve further up? 

I will be running a fuge off the return.


Thanks for looking


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## mmatt (Feb 12, 2012)

My personal preference would be to put a valve in case of any sort of failure. Also at least you can fine tune flow even more.


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## wtac (Mar 17, 2006)

A check valve is not needed nor should be relied upon unless the return output is a few inches below the water level. Ideally the sump should be large enough to contain water in a static/"off" state. Furthermore, a system running and static/"off" state test must be performed to determine the Max/Min water level of the sump. Somewhere in between those levels will be the running level for ideal skimmer depth, etc. Before you glue the return plumbing (overflow to display), do the following in case you have to drill an anti siphon hole...easier to do this now than later 

*How to determine Min Water Level:*
- Return pump is "off"
- Fill display with water until water begins to drain into sump.
- Add water to sump until it covers the return pump
- Turn on pump.
- Keep adding water to the sump until the return pump no longer sucks in air into the display aquarium.
- VOILA...the Minimum Water Level in a running state.
- *Mark the level on the sump*

Now, the fun part. Adjust your return outlets so that they are as close as possible to the surface without causing excessive splashing or pushing air into the water. When you are satisfied, unplug the pump and wait for the back siphoning to stop all the while keeping your eye on the water level in the sump. Hopefully when it all goes into a static state, the sump will contain all the water**.

Repeat at least 2 more times until you get repeatable results.

*How to determine Max Water Level:*
- Return pump off
- Fill sump until a max of 3" from the top
- Turn return pump on 
- Where the water drops that will be the Max water level.

For peace of mind, repeat unplugging and plugging in return pump to make sure that the sump will hold all the water in static/"off" state. If you see the water about to spill over, plug the pump back in and remove some water. Repeat until it no longer will over flow and stop at a level that you are comfortable with.

When you get repeatable results, *Mark the level on the sump.*

If noise isn't an issue, drill ~1/8" anti siphon hole on the return line in the overflow box area. Drill it somewhere along the horizontal run on the fitting on the underside. Do not drill the hole perpendicular to the surface but at ~45* towards the direction that the water is coming from, close to the overflow inside wall. Water will exit that hole and hit the overflow wall at an angle creating less noise vs splashing down into the overflow well.

HTH


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