Sputtering, left compartment in back empties out

[Soc]

Hi, I'm a super novice at this, my husband set up the tank (Biocube 14) but is out of the country right now. The input from the back left well to the main tank has been sputtering. When I turn the pump off, the back well fills up all the way, but as soon as I turn it back on the water level quickly goes down, well below the "min" level. I tried rinsing out the sponge, it didn't seem to help. The noise is driving me nuts, and the fish don't seem to be enjoying the bubbles either. Thank you!

 

[thegrun]

Have you been topping off the tank with fresh (Rodi preferably) water? It's likely evaporation has caused the level to drop.

 

[m0nkie]

^ +1

sounds like your overflow is making that sound due to lack of water. Top it off with fresh RODI. If not, the evaporation will increase the salinity. Not good for the fish