Question.

[cjrudy]

If the water level in my sump is perfect yet I need about another inch in my tank but when I add more water it just fills up the sump, does that mean my return pump isn't strong enough. I have a mag 9.5 with a 90 gallon tank, 30 gallon sump and about 4' vertical with a few 45 turns.

 

[AZDesertRat]

The water level in the display is regulated by your overflow box and your return pump. It will only get as high as the pump will raise the level until the wier or teeth in the overflow box reach equilibrium and flows back to the sump.
Do you have a hang on back overflow or an internal one? The hang ons can be adjusted up and down, internals are usually fixed and have no adjustement but are the preferred way to go.

The Mag 9.5 is similar in size to my Ocean Runner 3500 on my 100G and my level is about 1/2" up the overflow teeth. What are you using for return piping? Mag pumps benefit greatly from increasing the outlet piping at least one size, so if its 3/4" increase it to 1" and you will gain flow due to less head restriction or resistance to flow. Also use a few fittings as possible, every elbow, nipple or valve has an associated head loss reducing the overall flow. On the suction side is the pump submerged in the sump or is it mounted externally? Mags like a flooded suction with no restrictions so no sponges or foams and no fittings or valves on the suction if possible.

 

[melev]

If the tank doesn't fill up as much as you like, you'll have to either raise the overflow box (if it is a Hang On Back like Rat indicated), or you have to affix some type of material on the inside of the permanent overflow so that the water level has to rise higher to pour through the teeth.

Pictures always help.