Flow through sump

Was wondering how much flow should I have running through sump. My er rs100 has not been producing too much any more, have a air meter on its way to see if the pumps messed up.. Er dudes told me having too much flow in sump can effect skimmer if docs are low. Right now I have a 20 long sump with a mag 9 as return throttled back about half.. Was wondering if I should replace the mag9 with a mag 3-4? Thanks)

 

sump flow is different than skimmer flow.

 

As a general rule, the flow of the sump should be about 5X the capacity of the DT

 

actually its 5-10 depending on the livestock housed ( coral, fish only )

 

Cool thanks for the info) So 5-10X through sump.. My tank is reef, the drain dumps right into the skimmer section then it flows to fuge and finnaly to return. If that makes any difference lol