Reducing gph for return pump
 

Hi my return pump is 600gph and my eshopps overflow is 300gph. If I just use a ball valve on the discharge of the pump to reduce flow would that damage the pump? Or should I just split the discharge so half the water goes back to my refugium?

restricting the outlet is ok, but a bypass would probably be better.
never restrict the inlet of a pump.

+1 i've read of the water wearing down the ball valve til all hell brakes loose

You can cut most pumps back with a ball valve which actually reduces the power usage as well. I wouldn't push it more than 20-25% though. Maybe you could use some flow to run a GFO (and/or carbon) reactor(s). Which brand of pump do you have?

what I do. split it.

gate valve. After the pump.

Whats your reasoning for reducing the flow?

pump is double what my eshopp 300 overflow should handle

gate valve is good as a shut off valve not a reducing valve. Ball valve or globe will work better i think i might try ball or just divert the extra flow to refugium

If your pump is rated at 600GPH it won't actually pump that much given there is head pressure losses from both static head and pipe friction losses. In many cases you only end up with half the rated flow, there are online calculators you can use to get better idea.

A valve on the output is fine, it just adds to the head pressure, no different than adding more height.