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Glue a bulkhead?


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Hi all.  So, I've been battling a leaking bulkhead that is the only thing standing between me and my beautiful new tank.  The fish are in QT, and it has been cycled (though I am sure it's not helping taking it down all the time to rework this 😡 bulkhead!).  I've tried tighter, looser, I've added grease, I'd used different bulkheads.  At this point I am considering cleaning everything up, and gluing the bulkhead in place using the GE 100% silicone for plastic sheeting (same stuff that Dean uses) to fill the hole from the outside.  I know this will bond to my acrylic, the rubber gasket, and the PVC.  If it works, it will likely never leak.  My fear is that if it doesn't it will be an awful mess to clean up and I'll be back at square one with no ideas of what to do next.

So my question to all of you is this: just how bad of an idea is gluing this bulkhead in place?  Thanks in advance for the input!

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I am sorry you are having a problem.  What I don't understand is why is it leaking....if the hole in the tank is only slightly larger than the bulkhead than when you tighten it the gasket seals everything and your good to go...the only thing I can think of that would allow it to continue leaking is if the hole was much larger than the bulkhead then there would not be enough surface area for the gasket to seal against.  

Can you provide me a pic of the bulkhead in the hole without the nut on it so I may be able to see the problem.

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On 6/30/2021 at 12:24 PM, ARMYVET said:

I am sorry you are having a problem.

Thanks for commiserating!

On 6/30/2021 at 12:24 PM, ARMYVET said:

What I don't understand is why is it leaking....if the hole in the tank is only slightly larger than the bulkhead than when you tighten it the gasket seals everything and your good to go...

That's what I say!  Now tell the bulkhead that. 😁

On 6/30/2021 at 12:24 PM, ARMYVET said:

the only thing I can think of that would allow it to continue leaking is if the hole was much larger than the bulkhead then there would not be enough surface area for the gasket to seal against.

That's a good thought!  The hole is about 1.5-2mm larger on each side of the bulkhead when centered.  It's a bit looser of a fit than some of the other bulkheads I have, which I kind of have to wiggle in. 

But there is the thing, I was using this same hole for months without a problem.  Then I had to go and change the plumbing below.  Turns out the plumbing it was glued to couldn't take the extra water, and so I had to cut the old bulkhead assembly off.  The new one I fitted (same size and manufacturer) leaks.  It's kind of caught me by surprise.  I'll admit, because the setup worked before, I had no expectation this would be an issue.

Back to plumbing I guess...

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The 2 mms shouldn't be an issue as the gasket is wider than that. There's a reason it's leaking though. The question is, what is that reason. Can you see where the leak originates? Bulkheads are typically injection molded and it's possible there's a weak spot internally in the bulkhead. Maybe a fine crack where the bulkhead meets the tank. My big suspicion would be a defective bulkhead. When you talk about grease, I 'm assuming you coated the gasket with petroleum jelly. It's a very safe item to use to seal bad gaskets. If that didn't work, I'd suspect an issue with the bulkhead itself. A new bulkhead would likely solve your problem.

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I personally want the bulkhead to be as large as will fit in the hole so the gap between the wall of the bulkhead and the hole is minimal.  
That gives the gasket as much surface area on the glass as possible to make a seal. I too use a bit of Vaseline on the seal and threads when I goto set the seal. 
if all of that fails get a new bulkhead @gardenman may be correct that there is a flaw in the bulkhead.  If you get a new bulkhead and it works.  Beat the living hell out of the one that didn’t work with a hammer.  That will teach it to screw with you 😂

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On 6/30/2021 at 8:12 PM, OnlyGenusCaps said:

Thanks for commiserating!

That's what I say!  Now tell the bulkhead that. 😁

That's a good thought!  The hole is about 1.5-2mm larger on each side of the bulkhead when centered.  It's a bit looser of a fit than some of the other bulkheads I have, which I kind of have to wiggle in. 

But there is the thing, I was using this same hole for months without a problem.  Then I had to go and change the plumbing below.  Turns out the plumbing it was glued to couldn't take the extra water, and so I had to cut the old bulkhead assembly off.  The new one I fitted (same size and manufacturer) leaks.  It's kind of caught me by surprise.  I'll admit, because the setup worked before, I had no expectation this would be an issue.

Back to plumbing I guess...

I recommend installing larger bulkheads, if they can fit; and then get reducers to fit the existing PVC.

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The two millimeters on each side would add up to four millimeters if the bulkhead was all the way to one side. That's 0.157" (a tick over an eighth of an inch, about 5/32's of an inch) which is still much smaller than any bulkhead gasket I've seen. My gut says it's a bulkhead issue. If the bulkhead got over tightened at some point it's possible a hairline crack developed where the bulkhead meets the tank. The design of a bulkhead is such that you're trying to pull that inner face through the tank to compress the gasket. If you pull too hard (overtighten the nut) it's not impossible to crack that section and cause a leak. 

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Have you made sure that the glass where the gasket contacts is perfectly clean? Make sure that there isnt any kind of residue from when the tank was set up before. Is the bulkhead brand new or was it used before? I have found that if I take a bulkhead off I always replace the gasket, never had one seal for me when re-using. Something else, are you putting the gasket on the correct side? The gasket always goes on the flange side, not the side the nut goes on. I'm just throwing ideas out there of things that I I have found over the years of having drilled tanks or have heard others have done. Good luck, and if all else fails, a new bulkhead can be bought.

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On 7/1/2021 at 6:35 AM, Andy's Fish Den said:

Have you made sure that the glass where the gasket contacts is perfectly clean? Make sure that there isnt any kind of residue from when the tank was set up before. Is the bulkhead brand new or was it used before? I have found that if I take a bulkhead off I always replace the gasket, never had one seal for me when re-using. Something else, are you putting the gasket on the correct side? The gasket always goes on the flange side, not the side the nut goes on. I'm just throwing ideas out there of things that I I have found over the years of having drilled tanks or have heard others have done. Good luck, and if all else fails, a new bulkhead can be bought.

Where do you find just the gaskets for the bulkheads? I never have found them!

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Just double check that the bulkhead itself is clean of any debris or casting marks where it meets the gasket as well as clean tank where the gasket meets it, make sure the gasket is on the inside of the tank not the outside (Brain fart). If it still leaks no matter what, i think i'd do the same as your thinking and put a thin coat of silicone on each side of the gasket and let it cure, not knowing the underlying reason.

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I love this forum!  Look at all the wonderful and helpful advice I got on an esoteric question.  It's fantastic!  Thank you all!

On 6/30/2021 at 7:52 PM, gardenman said:

The question is, what is that reason.

Agreed.

On 6/30/2021 at 7:52 PM, gardenman said:

Can you see where the leak originates?

Sadly, I can't.  It drips out the bottom, but I strongly suspect that has something to do with gravity.  🧐

On 6/30/2021 at 7:52 PM, gardenman said:

If that didn't work, I'd suspect an issue with the bulkhead itself. A new bulkhead would likely solve your problem.

That's a good possibility at this stage I suspect.  Now I see why a union would have been good to install.  That was I don't have to remove an entire assembly when just one end goes off.  Luckily, I can still install one, now that I have to cut into the line again anyhow. 

On 6/30/2021 at 8:08 PM, ARMYVET said:

I personally want the bulkhead to be as large as will fit in the hole so the gap between the wall of the bulkhead and the hole is minimal.

Totally agree.  This is the first time I didn't just size the hole saw based on my feelings about how big the hole should be.  I followed manufacturer's instructions.  That may have been a mistake.

On 6/30/2021 at 8:08 PM, ARMYVET said:

Beat the living hell out of the one that didn’t work with a hammer.  That will teach it to screw with you 😂

There may be a follow up video coming...  🤣

On 6/30/2021 at 8:10 PM, d23perry said:

I recommend installing larger bulkheads, if they can fit; and then get reducers to fit the existing PVC.

Next size up is much larger than the hole that exists.

On 6/30/2021 at 8:25 PM, gardenman said:

If the bulkhead got over tightened at some point it's possible a hairline crack developed where the bulkhead meets the tank.

The first time I attached this bulkhead I only hand tightened it.  Perhaps I am stronger than I realized!  🦸‍♂️  I'll admit though that this last time when it leaked more I did use a pair of channellocks.  So, if you are correct and there was a hairline, my using the pliers could account for the increased leaking I saw after applying the grease.

On 6/30/2021 at 8:25 PM, gardenman said:

My gut says it's a bulkhead issue.

I think that's the problem.  My gut is saying "please make this plumbing issue stop at all costs!"  Not as useful, to be sure. 

On 7/1/2021 at 5:35 AM, Andy's Fish Den said:

Have you made sure that the glass where the gasket contacts is perfectly clean?

It's acrylic, but yes.  I wiped it all off and cleaned the surface.

On 7/1/2021 at 5:35 AM, Andy's Fish Den said:

Is the bulkhead brand new or was it used before?

It leaked when brand new, but my monkeying with it only made it worse.

On 7/1/2021 at 5:35 AM, Andy's Fish Den said:

Something else, are you putting the gasket on the correct side? The gasket always goes on the flange side, not the side the nut goes on.

Yes, it's on the proper side.  Funny enough, when I first installed a bulkhead, more years ago than I care to admit, I totally installed it with the gasket on the wrong side.  It's good to check.

On 7/1/2021 at 7:35 AM, Scott C said:

i think i'd do the same as your thinking and put a thin coat of silicone on each side of the gasket and let it cure, not knowing the underlying reason

Though I am not convinced I have a cracked bulkhead and I am going to replace it tonight, I'll admit, I'm still a bit tempted to glue the new one in.  Probably making more trouble for myself in the future, but that's future me's problem.  Am I right? 😜

On 7/1/2021 at 7:38 AM, Steve A said:

Have you tried a thin O-ring on the water side of the tank?

That's an interesting idea.  I'd still have to cut off the current assembly to do that, so I'll likely just use the gasket that comes with the new bulkhead.  That's part of the problem.  You can really "test" a bulkhead before gluing everything together.  It's kind of an all in situation.  Certainly, in my case this is why I am so eager to try little tweaks rather than replacing the bulkhead.  Even when that is likely the issue. 

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