Return outlet design

[CarrieB]

We re-plumbed the new used tank to implement a herbie system. The return pipe comes up over the back and points downward. The old system used this nifty splitter that you can angle in different directions so we put that on. However, when we tried the pump off test, I realized that it was going to siphon the tank to a greater depth than would be desirable, so we took it off.

What are you using on your return outlet? Anything to point the flow in a particular direction? Seems like it would be valuable...

 

[thegrun]

Drill a 3/16" hole in the outlet just below the running water depth and the hole will allow enough air into the drain line when the pump is turned off to break the siphon.

 

[D-Nak]

Drill a 3/16" hole in the outlet just below the running water depth and the hole will allow enough air into the drain line when the pump is turned off to break the siphon.

This.

 

[CarrieB]

Brilliant! [emoji1]

 

[RocketEngineer]

I make sure one of my outlets is near the surface of the water when the system is running so that as soon as the pump turns off it pulls in air. A hole can be plugged by a snail or a bit of algae, the whole opening is much harder to block. Plus I don't have to clean it out regularly.

 

[jacksonpt]

I'm not using anything for directional flow. Flow in my display comes from my powerheads, so the return really only serves 1 function - to return water to the display.

The idea to drill a small hole just below normal water level is a good one. You might also be able to position the return outlets closer to the surface so less water siphons back down.

Lastly, could this be a sign that your sump is too small and/or too full for your display? One of the key considerations for a sump is that it be able to handle backflow from the display. Things like drilling the hole in the return or repositioning the outlets will certainly help... just thought I'd mention it.

 

[billdogg]

I make sure one of my outlets is near the surface of the water when the system is running so that as soon as the pump turns off it pulls in air. A hole can be plugged by a snail or a bit of algae, the whole opening is much harder to block. Plus I don't have to clean it out regularly.

Exactly what RE said.

 

[eb2292]

I drill a couple holes in each return line to make sure that if one is blocked, the other has a low chance of also being blocked.

 

[CarrieB]

Thanks everyone. The sump came with the tank and definitely is on the small size. I think it's sufficient to hold the water down to the overflow line, I'm just not sure how much more than that it would hold. In any case, it's not something I can replace now so I need to work with what I have.

 

[kmbyrnes]

You could also put a 90 degree elbow on it and that would let you set the depth wherever you need it. In all my tanks, the return will suck air at about the same time the water level drops below the teeth of the overflow.