Oh I am SOOOO frustrated!!!

[mark]

Sorry to hear about the crack but trying to understand how.

If the flange and the nut is fully supported by the glass (correct hole size for the bulkhead) and faces are smooth, would think when tightening, the plastic threads would strip before you could get enough compression to shatter the glass.

[Myka]

With really thin glass it's actually quite easy to crack it by over tightening the bulkhead.

I haven't decided what I'm going to do. right now I'm leaning towards just replacing the pane so I don't have to redo all the baffles. Or I might just build one from scratch so I can use better dimensions and get more gallons in there. I dunno, right now I'm trying to ignore it.

[banditpowdercoat]

Originally Posted by mark

Sorry to hear about the crack but trying to understand how.

If the flange and the nut is fully supported by the glass (correct hole size for the bulkhead) and faces are smooth, would think when tightening, the plastic threads would strip before you could get enough compression to shatter the glass.

If there is any irregularities on the bulkehad flange, it can easilly overstress thin glass.

[Marlin65]

One more reason I love tempered glass. All my tanks and sumps are tempered.
Maybe consider going tempered on the next tank it is not that much more, 7x stronger and has flex to it.
They will drill the hole before they temper.
Tempered is like heat treated steel they heat it red hot to align the particles and then cool it rapidly with big fans. Think of it as the difference between mild steel and tool steel.

[SmallFry]

Originally Posted by Myka

[rant]
So here I am puttering around my tank today trying to get the stupid bulkheads to quit leaking so I can finally get my sump running. I had them fairly loose since I'm paranoid about cracking the glass, so of course they leak, and need to be tightened up more. I am such a procrastinator. I am tightening up the last bulkhead and CRACK. There goes the sump.

SO I siliconed the crack thinking that would prob do the trick since the crack is only about 3" long, and 3 hours later I am messing around in my planted fw tank and I hear CRACK. Another crack splits up the other side of that bulkhead. Oh for hell...

Now I have to go buy a new sump, reinstall the baffles, drill the holes for the bulkheads, buy a bunch of new plumbing pieces, and basically redo the entire thing since I can't get the plumbing apart to repair it. I'm ready to kick the sump.
[/end rant]

I think you earned that rant...

Firstly, I have never put a bulkhead in a tank, so this may be a dumb idea. No doubt someone will else with more experience will gently point out if it is.

When fitting stuff to boats (like skin fittings - which are basically the same as bulkheads) I often used to bed it on a layer of silicone on the underside of the flange, tighten very lightly until the silicone cured, then tighten a bit more when the silicone is cured (or at least partially). The reason being that the layer of silicone under it is bonded to the fitting and the boat/glass/whatever, and is quite soft so it takes up any irregularities with less pressure. If you tightened it up too much before the silicone cured it often leaked because most of the silicone was squeezed out from between the two.

Admittedly a boat hull is (hopefully) a bit more resilient than a glass aquarium panel, but maybe worth a try...

Robin.

[Myka]

That's kind of a cool idea Robin. At least for smaller tanks with thin glass and little water pressure.