System 2 tank close to overflowing- Why?

[Damion Clark]

Guys, I could use your help. I have 2 system 2 salt water tanks. One of them has nearly an inch to the top and can accommodate several gallons in the return reservoir before completely submerging the bioballs. My other tank will only hold several cups of water in the tank return before the water level overflows the rim of the tank. This makes it very challenging to keep enough water in the tank before it starts evaporating and the pump starts sucking air. I am woken up every week by the t

ank reaching the return pump's minimum water level before it starts sucking air and blowing bubbles. I'm totally at a loss as to why this tank is doing this. See pics. Your help is most appreciated.

 

[TheEngineer]

Looks to me like something is blocking the flow in the overflow. If you have bioballs in there I’d suggest removing them and see if the problem stops.

 

[vetteguy53081]

Pull your pump and clean it, especially the intakes and Impeller area. The pump cannot keep up with the incoming water due to poor delivery. Looks like a lot of slime in the sump area of tank. Take a Clean rag and wipe the slime off the surfaces especially in the one where the pump is housed.