What overflow pump do I need? I cant remember.

[briand7878]

I have an overflow on the back of my tank with the u tubes. Im overseas right now and its giving my girlfriend fits when she forgets to top it off. The water in the u tube breaks suction and stops flowing. I know there is a pump that will create the suction that goes into the u tube to keep it flowing. Does anyone know what im talking about? I need to know what it is called so i can order one.

 

[natclanwy]

Its called an aqualifter but you don't need it. Your U-tube should never lose syphon even if your tank is low on water. You have a different issue more than likely the culprit is a return pump that is either too small or clogged up. With a HOB overflow you need to have a pump that is rated for 70-100% of the overflows rating after you subtract for headloss. If you have a pump that is smaller or is clogged up and not flowing properly the water travels through the U-tube too slow to evacuate any air bubbles that make it into the tube.
If you can give me some details on what size your pump and overflow box is and how much verticle pipe and what size you have on your return pump I can make a better decision on what the problem is and how to fix it.
U-tube style overflows are almost as reliable as a drilled tank if setup and maintained properly, if you add an aqualifter to them they will become very unreliable.

 

[briand7878]

Ive never had trouble before I left it with the girlfriend. She forgets to fill the sump and for some reason the u tubes do lose suction. When she fills it back up it just pushes the water to the top and is usually dangerously close to an overflow. My friend has to come over and restart the siphon. I have a quiet one 4100 which is plenty of pump for my setup. I just wanted something to get the flow going again. Im almost done over here and will never have to worry about it again.

 

[natclanwy]

It could be that when the sump empties the pump is sucking air slowing down the pump rate which is allowing air bubbles to accumulate in the U-tubes.
That being said you keep mentioning U-tubes in plural so I am assuming you have a dual U-tube overflow. The smallest dual U-tube overflow I can find is rated for 900gph. I did some guessing since you didn't provide any details on your plumbing or exactly what size your overflow is but anyway I assumed you have 4ft of head and used 3/4" hose or pipe for the return on your pump and when I calculated the head loss your pump is only returning about 600gph to your tank. If you follow my recommendation for pump rates your pump is just at the minimum recommended size to maintain the siphon in your U-tubes and this is only if you don't have any valves or other restrictions in your plumbing and your pump is operating at peak performance.
Another reason you might be having issues now is your pump is not pumping as efficiently as it did before you left and since its riding on the bottom of the recommended pump size your U-tubes are collecting air bubbles and losing siphon.
A quick fix is to just remove one of the U-tubes then keep an eye on it and make sure that the single U-tube can keep up.
Take my advice and don't add an aqualifter to your setup, I have used them and they are extremely high maintenance to keep them running somewhat reliably. Your U-tubes by nature are extremely reliable if you have the proper flow rate, but if you add the aqualifter they will be just as unreliable as the aqualifter is.

 

[briand7878]

Ok, sounds good and thanks for your help.