Overflow help

[Fishyj]

I have a 13.5 gallon tank that I did a diy overflow to it without drilling the tank. It hangs on the back and is 3/4 inch until it enters the cabinet. I have it connected to a 1/2 hose going to my sump/fuge. The return is 1/2 hose and I am using a mj1200 which has a 295 flow rate and I am wondering if this will work. I am hesitant to start this sump up with the live stock in the tank. Any advise?

 

[Triggreef]

Need more info. You could just mix up some more Saltwater and dump it in manually to see if it works.

 

[Fishyj]

I ended up doing just that and then found out I needed to add a valve on the inlet to match the return pump.

 

[Fishyj]

Over night, my return part of the sump dropped and my tank level went up. It looked like it was holding before I went to bed. Any ideas on this? Do I need a gate valve instead? Should I remove my filter rack and sump sock?