Is a gate valve needed if using a DC return pump?

[C_AWOL]

I agree, but my question was if you can accomplish the same result via a DC pump.

Unless you can magically adjust the drain hole size some other way or have a grossly over powered pump for your drain hole size to create a siphon anyways then no.

 

[Miami Reef]

That’s absolutely not true.


Valving back the output of a centrifugal pump (i.e., increasing static head) does no harm to the pump. It can even be fully dead-headed without damage -- aside from potential overheating due to lack of flow to dissipate heat.

Increasing head doesn't increase pressure in the pump; it simply moves the operating point left on the curve. The pump actually does less work because it moves less water. In fact, it's often operating closer to its best efficiency point (BEP) when slightly valved back, rather than running wide open.

At BEP - the pump is moving the most water per watt consumed -- thus running cooler and typically with less vibration or noise.

This is fluid dynamics 101 :)

Thanks for this information!

 

[twentyleagues]

It seems counterintuitive to think valving back actually help the pump last longer. Coming from my reef years ago run by Reeflo pumps this was exactly what their tech support recommended. I am not a scientist or mathematician but valving the flow back keeps the water in the pump "longer" allowing more heat to be transferred it also increases head pressure which these need to function properly (I know this isnt 100% correct terminology). Reeflo are not a submersible pump so its a bit different they are also not dc controllable but they work on the same principals.