External Overflow Troubleshooting

[ROlympia]

Hello,

I replaced a Vectra M1 with a Reef Octopus Varios8 (because that's just about all that was available that met my needs). The Varios8 overwhelmed the overflow, an Eshopps 1000 model, on any setting except the lowest. I replaced it with the 1800 model and the pump overwhelms it as well.

I have 1.5" PVC from the 1800'a bulkhead and 1" flex PVC at the last 12" or so going into the sump. The flex PVC needs to be trimmed because it is 2" or more below the water surface. However, that does not appear to be the problem. Rather the overflow tube seem unable to keep up. I say this because when I increase the pump to the second speed setting, the water backs up inside the overflow box inside the tank but flow does not appear to increase much, if at all, on the other side of the overflow tube.

I lowered the internal box thinking it may be too high, therefore restricting the flow of the overflow tube. I subsequently raised it again, thinking perhaps the water level was too low and not pushing the water through properly. Neither seemed to make a difference.

Any suggestions or is an external overflow simply insufficient for this pump? I intend to replace the tank someday but that is not a near term goal. This tank is tempered glass.

Thanks

 

[Vinny Kreyling]

Can you use pool hose OVER the drain bulkheads increasing the size?
It has 3 drains like a bean right? If so something is amiss.

 

[ROlympia]

It has two. It seems to be the overflow tube itself that has the issue since there is no noticeable increase in flow when the pump speed is increased; the water rises inside the tank.

I thought about adding a second overflow tube but the single seems much safer - the air doesn't gather at the top of the tube like it does with two tubes.

 

[Vinny Kreyling]

Shortening the drain hose should help some by lowering the back pressure on the drain.
If there is 1 overflow tube 1" ID it should flow about 600 GPH. You will need 2 to max the flow of the box. As you surmised the flow has to "pull" any air from the tube completely or eventually you run into trouble.