Pvc overflow

Return pump not good enough to equalize water level in sump.

I have a 120 gallon aquarium with a diy pvc overflow made the same way as the videos on YouTube but it seems as though the overflow puts to much water into the sump then looses it's siphon the return pump then pumps the water back into the main tank till there is no water left in the sump the pump is a 317gph pump and I'm using 1 1/4" pvc. Any help would be great.

 

From what I've read(not experienced yet) one solution to the overflow outrunning your pump would be to add a ball valve to your overflow. That way you can tune your drain rate.

 

Ya I tried that but it was either to much overflow or not enough spent 10 days trying to fine tune it but no luck. Thanks tho.

 

Could you use a float switch to set your upper water level in the fish tank and keep the overflow slightly slower than the return?

 

The overflow is about 2 1/2-3" lower than the return already. I think I'm just going to redesign the overflow with a pump. Going to get the exact same one that I have for return so that it's all equal.

 

So I fitted a pump to the overflow and all is good. Only thing is you can see a bit of the hose in the tank

 

That's awesome!

 

Thanks, trying to figure out how to make it work without the hose being visible