Terrible Advice Tuesdays (T.A.Tues): The Leak-Proof Installation Method For Bulkheads


Terrible Advice Tuesdays (T.A.Tues): To ensure your bulkheads don’t leak, glue them to your tank with PVC cement.

The rest of the story: I about fell out of my chair (again) when I heard this one. A couple of things here:

#1: A bulkhead will form a good seal and not leak when installed correctly. No glue is needed.

#2: If you glued your bulkhead to your tank, if you ever wanted to remove it, good luck. Removing it will be a royal PITA especially considering how tight of a space you’d be working in.

Finally…as outlined in my No-Nonsense Guide To Setting Up A Saltwater Tank Vol 1 (currently on sale for 30% off), remember that the rubber gasket on the bulkhead goes on the inside of your tank!

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Comments for this article (14)

  • George says:

    Funny, I can’t believe the crap people come up with that is so far off the mark! I have seen people swear that you should not use primer or glue, or you have to give your plumbing days to cure, or an acid bath before use.

    The latter would not be harmful if the acid bath is a vinegar and RO mix, but certainly not required. If you are going to bother doing that you should probably run some kind of brush or sponge through the tubing while you are at it to insure a good cleaning. In the end it sounds like a pain in the butt to try and address what should be a not problem in the first place.

    Getting back to bulkheads and things you want to remember, remember the finished side (the side with out the nut) goes in the water.

    I have seen people do some interesting things with bulkheads, where they reverse them. I do not recommend that, but if you have a situation where you have to have the unfinished side in the water then you want to be sure to use a gasket on both sides of the bulkhead.

  • Merne says:

    I think I disagree with you George. The gasket should always be on the water side, and the nut should always be outside the water. Think about how your overflows are plumbed. I’ve never seen the nut side in the water, although you’re right that if you do this you’ll want a gasket on both sides. It will still leak some if you do it this way because the water travels the threads from the inside.

  • Merne says:

    bah, I just can’t read. I totally agree with you George 🙂

  • Kurt says:

    The gasket is always on the opposite side of the nut . If the gasket is next to the nut then when you turn the nut it deforms thus how would it make a good seal . As far as up down sideways etc does it really matter so long as you have a good seal ? What if you run the bulkhead upside down into your overflow? If you have limited space under a tank it gives you a few extra inches to make a turn etc, so if it seals with the nut side down it will seal in the nut side up. Unless you have extreme down force from water pressure like in a 100 foot deep aquarium ……….even then a water tight fitting is water tight.

  • Will says:

    This is true, Mark. In fact, by adding anything between the rubber gasket and the tank (like silicone, PVC cement, etc.) CAN actually compromise the gasket and create a leak… In other words, doing this is useless at best or counterproductive. BTW, this goes for any plumbing connections with rubber gaskets like compression fittings.

  • Kyle O says:

    As I can’t even imagine why it would occur to anybody to use PVC cement to adhere the bulkhead to glass……….thinking about it, I can’t imagine why using silicone would ever cause a problem. Seems to me that silicone would help with the gasket cracking problem that will occur a few years down the road by acting as a sealant.

    That is like saying that glass tanks should not use silicone in the joints putting it together, or that it will eventually leak (no matter what).

  • Forrest says:

    People do really dumb things. Like use PVC cement to bond PVC fittings to PB pipes. (doesn’t work, btw… I know.)

    Anways, when I install bulkheads, after cutting the hole for the bulkheads and placing them in the tank, I would tape them in place on the inside and from the back side (nut removed) fill in the area between the threads and the glass w/ silicon. Then I would attach the nut and screw it down hand tight. That way the silicon didn’t interfere w/ the gasket and any excess would squeeze out the backside (as that is the open side) and actually hold the nut in place after the silicon hardened.

    Removal is very easy too. Just cut off the plumbing behind the union (which has to be done anyway), remove the nut, and twist the union to break the silicon before pushing it out.

  • Dylan says:

    I know you guys will probably rip me for this but I siliconed my return bulkhead to the tank because I was getting a little leak. In retrospect it probably was because I didn’t tighten it enough, but I have not had a problem.

  • Speedy says:

    I silicone the bulkheads always just for piece of mind. Rubber is great but silicone can get in all the little spaces. I have had to remove it and two inch bulkhead with silicone with a fresh razor blade…took me only 30min tops to remove, well worth it if you ask me.

  • Pierre Bouic says:

    I have always used silicone to give the union and threaded female fitting the proper seal. Now that bulk heads with gaskets are available the essentials are the same. I’m speaking from my plumbing experience tied in with many installations as a tank installer & maintenance guy who ran Pierre’s Aquarium service in Aust. north of Sydney.
    I’ve seen it done wrong & the first one I did for myself wrong proved it. I mean with just plumbing male & female union connectors and silicone I start with the male part with a ring of silicone around the area of surface contact at the base of the threaded section placed down in the 38mm hole (1.5 inch) then let it dry & wait 24hrs before screwing the female part on from the underside, then a bead of silicone around the inside of the tank where the PVC fitting meets the glass, the wait 24hrs to set & cure before putting the standpipe into the bottom up to the height you want the water to drain at. This too is important as the weight of H2O will put a lot of strain on the weir so take it up to 3/4 of the water level to drain. The first 4 ft tank I converted for myself was leaking soon because I did it back to front and water travelled down the inside of the pipe threaded area of the fitting. Since the first wrong experience all my installs are still leak free from 12 years since they were done on many jobs. Having been taught by a tank maker to cut glass & make tanks
    I’ve built my 180 gallon tank from 10mm glass from scratch,ten years on its still leak free using acetic cure glass silicone. From that to 14 tanks in my tank room and all the timber stands ( yes Mark my own tank room).

  • Scott says:

    Just as a safety measure, I did apply a thin film of aquarium grade silicon sealant to the rubber flat seal to ensure no leaks. I used screw type bulk heads so if I ever need to remove my PVC fittings on either side of the bulkhead, I simply unscrew them. I never plan on removing my bulkheads anyway so I figured applying the sealant was worth it. My tank is 6 months old and no leaks thus far (Knock on wood).

  • rich says:

    any one know how to unscrew and screw a 2 inch bulkhead for a water fall its so tight i can’t unscrew it to put it on

  • rich…rightie tightie, leftie loosie.

  • Jeff says:

    Can I put the bulkhead in upside down? So that I can glue in a ball valve (to stop the flow out of the tank if i need to do maint on the sump? If not how do you go about removing the bulkhead so it doesnt stick out the tank if it has to be moved?

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