Bulkhead Leaking. Need advice on sealant.

[Dan I]

I had my return line bulkhead leak before but I fixed with silicone. However, I restarted tank and it is once again leaking. I changed bulkhead and it still leaking. Gasket is installed inside the tank. Is there any sealant I can use to stop the leak.

 

[JoshH]

Pictures??? What type of bulkhead is it?

 

[Dan I]

It is leaking on the bottom part of the gasket. I drained enough water to fix the issue. I have tried tightening it and it still leaks pretty bad.

 

[Big G]

Pure silicone is your only choice. Other than that is to replace the bulkhead. Sometimes they crack and only open a bit when tightened. Or they are not square to being with and need to be replaced with a bulkhead that is square to the glass. Warped bulkheads are not good.

 

[Dan I]

Pure silicone is your only choice. Other than that is to replace the bulkhead. Sometimes they crack and only open a bit when tightened. Or they are not square to being with and need to be replaced with a bulkhead that is square to the glass. Warped bulkheads are not good.

Just got this bulkhead almost 10 minutes ago from Amazon.

 

[redfishbluefish]

"Gasket is inside the tank"

What is critical with the gasket, regardless of how the bulkhead is installed, is that it goes on the side with the flange. So again, if the flange is on the inside of the tank, that's were the gasket goes. If the flange is on the outside of the tank, the gasket goes there. And it doesn't matter what way the bulkhead goes.

 

[Dan I]

Oh, you're right. I don't know how I forgot that. Let me try that and I'll report back. Thanks so much!!

 

[JoshH]

"Gasket is inside the tank"

What is critical with the gasket, regardless of how the bulkhead is installed, is that it goes on the side with the flange. So again, if the flange is on the inside of the tank, that's were the gasket goes. If the flange is on the outside of the tank, the gasket goes there. And it doesn't matter what way the bulkhead goes.

1+ RFBFs advice, also have an eye on the threaded joints, teflon tape isn't ideal for sealing PVC threads

 

[Dan I]

UPDATE

Leak is fixed. Thanks so much for the help. Also, I'll look up the teflon tape ordeal when I get a random flow generator from VCA. Once again, thanks again guys. I don't know how I thought I installed it right when I did not. You guys are the best.

 

[JoshH]

UPDATE

Leak is fixed. Thanks so much for the help. Also, I'll look up the teflon tape ordeal when I get a random flow generator from VCA. Once again, thanks again guys. I don't know how I thought I installed it right when I did not. You guys are the best.

Excellent :) and best to use PVC thread sealant on threaded fittings although I wouldn't worry about tape or sealant inside the tank, just outside.

 

[don_chuwish]

... if the flange is on the inside of the tank, that's were the gasket goes. If the flange is on the outside of the tank, the gasket goes there. And it doesn't matter what way the bulkhead goes.

Really? I always thought the flange should be on the inside (wet side) and the nut on the outside. Either way you get a seal I guess, but it just feels right to have it sealed from the inside. Plus I didn't like the idea of putting the gasket on top of paint.

 

[rockskimmerflow]

Really? I always thought the flange should be on the inside (wet side) and the nut on the outside. Either way you get a seal I guess, but it just feels right to have it sealed from the inside. Plus I didn't like the idea of putting the gasket on top of paint.

Ideally the gasket goes on the inside of the tank, but if the flange is on the outside there really isn't a way to securely seal the gasket on the inside any longer. The nut that tightens down the bulkhead is NOT designed to provide even compression on the rubber gasket the same way the flange is. So @redfishbluefish is correct in stating that the gasket needs to be paired with the flange in any case.

In general I like to hit the gasket with a little bit of DOW Corning Molykote to get it to really lock up on the flange and lip of the tank material it's sealing through. I have had defective bulkheads though without a doubt- usually an imperfection in the flange surface creating a space that won't sit flush no matter how tight you get the bulkhead.

 

[don_chuwish]

Ideally the gasket goes on the inside of the tank, but if the flange is on the outside there really isn't a way to securely seal the gasket on the inside any longer. The nut that tightens down the bulkhead is NOT designed to provide even compression on the rubber gasket the same way the flange is. So @redfishbluefish is correct in stating that the gasket needs to be paired with the flange in any case.

Yes definitely gasket with flange - but I'd always then choose to put flange & gasket on the inside. Kinda thought it was the only correct way.