Newbie Bulkhead quesion

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Aquarium Advice Regular
Feb 8, 2008
Hey guys, this is my first time dealing with setting up bulkheads and I'v got some questions. Is the rubber O ring that comes with the bulkhead supposed to be on the top of the bulkhead inside the tank? Or on the bottom of the bulkhead outside the tank? Also, does everyone use silicon to make sure it does not leak? Or just tighten it up?

ALSO! :) another newb question, I am assuming that the bigger drilled hole is the exit and the smaller is the return?
Put the seal against the bulkhead not the nut. Whether it is inside or outside of the tank doesn't matter much. I have done it both ways depending on the application. I do not use silicone to seal around the bulk head. Just don't over tighten the bulkhead because it can break.
The rubber gasket should go on the water side of the bulkhead, not the dry side with the nut. You want to prevent the water from seeping thru the bulkhead threads.

Both hole are the same on my tank, but the bigger (1") should be the drain and smaller (probably 3/4") is for the return.
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