Which side of the bulkhead gasket should be against the glass?

[TurboTimmy]

My bulkheads came with the gaskets in a bag and one side has two little rings that protrude a tiny bit, the other side completely flat.
I'm unsure if one side is meant to be against the glass the other side the flange or if it even matters.

My other tank, the gaskets are flat on both sides...

Thanks!

 

[carbondave]

I faced the same dilemma recently. I opted to put the flat side against the glass. Took a little bit of tightening but it doesn't leak. That said, I took some advice I found online to gasket both sides of the glass.

 

[vetteguy53081]

My bulkheads came with the gaskets in a bag and one side has two little rings that protrude a tiny bit, the other side completely flat.
I'm unsure if one side is meant to be against the glass the other side the flange or if it even matters.

My other tank, the gaskets are flat on both sides...

Thanks!

The flat with gasket goes on inside of tank (wet side) and other with the little knobs on outside of tank

 

[EeyoreIsMySpiritAnimal]

The bulkhead gasket goes on the flange side (not the nut side) REGARDLESS of whether this is the wet or dry side.

 

[N1tew0lf1212]

The gasket goes on the flange side (not the nut side) REGARDLESS of whether this is the wet or dry side.

This is the most correct answer ive read recently

 

[ca1ore]

My bulkheads came with the gaskets in a bag and one side has two little rings that protrude a tiny bit, the other side completely flat.
I'm unsure if one side is meant to be against the glass the other side the flange or if it even matters.

My other tank, the gaskets are flat on both sides...

Thanks!

I don’t think it really matters. Most of the gaskets I have used are flat on both sides, though some had the small ridges. Never really understood their purpose, and I’ve installed them both ways.