Kepping proper sump flow?

[at]

Im hooking up my sump and it occured to me... how do people keep the flow rates matched perfectly? I had a wet/dry years ago.. and every other week or so Id come home and the thing would be running dry.. yet it was just fine before that. Is the trick to keep the gravity drain at a slightly higher rate than the return pump so it shuts the overflow off every now and then and "catches up", or is there another trick?
Thanks!

 

[dmc888]

You have the right idea.
Better to be safe and have a little extra gph on the overflow.
I have about 510gph actual gph at 4 ft head with a 600 gph max overflow.
No problems in 3 years. Its pretty quiet too.

 

[shiby1510]

how do u figure out ur gph from the overflow??

 

[dmc888]

Best bet is to check with the manufacturer.
If not i would try posting here and see if someone knows.
Try posting brand,model,and size tubing.
Google search would work too.