Has anyone ever had a tank resealed
 

Hey everyone I have a 120 gallon tank that is drilled for a closed loop it has a dual overflow but one of the glass panels is cracked. So I am looking for a local company that can fix the tank and reseal it. Has anyone ever dealt with a company that does work on glass tanks.

Not the panel of the tank the over flow is cracked just for clarification

I have done it myself. Just use a blade and cut out the silicone in the corners. Re-caulk with clear silicone from Lowe's or Home Depot. Don't be fooled by all the different silicone choices. 100% silicone, clear is all you need. Apply masking tape about 1/4" from the corners alone all joints to provide a clean edge. A credit card work great to smooth out the silicone. A little silicone goes a long way.

You should not need to dismantle and separate the glass panes, unless there is a problem with the seal between the panels. If you do, only use masking tape to hold the panes together. I attempted to repair a 150 once and clamped the glass. As the silicone dried, it expanded and the glass broke.

Never heard of silicone expanding as it cures, especially enough to crack tank glass. Bummer.

I hadn't either. It made a very loud bang about 4 hrs after I clamped it. It was easily 3/8" glass, maybe thicker.

don't know, but I would think clamping pressure before silicone expansion.