Drilling Tank: Small chunks

[Doug]

I find clamping a wood piece on each side, one with a predrilled hole and limited pressure on break through helps with chipping.

[e46er]

silicone the bulkheads.
Ive never not siliconed them but glass cracks so easily when pinches Id rather silicone and hand tight than no silicone and wrench them...........

[gregzz4]

But when you use silicone sealant you can't re-tighten the bulkhead once the silicone is cured.
So what happens if it's not tight enough to start with? Or starts to leak a week later? Your method works for you, but the next guy may not do it the same as you and end up with a difficult fix.
IMHO silicone on bulkheads is messy and not necessary.

Just wet the gasket before installing to ensure it doesn't bind during tightening.
Hand tight, then a quarter turn and you're done.

And if it ever needs to come apart later on there's no grief.

[sphelps]

You have to drill from both sides to avoid chipping on the breakthrough. Also silicone on bulkheads is just silly.