We bought a tank off of fb marketplace that already had a hole drilled for the bulk head. We set up all the pipes and filled the tank with water to make sure it all works correctly. There's a leak coming from the bulk head. We tried to tighten the bulk head but it's still leaking. We think the hole was drilled too big. Is there anyway to fix this? Can you use some kind of sicilone or sealant around the bulk head? We're trying to find a way to fix this before going out and spending the money on a new tank. Any help we be awesome!