Leaking Bulkheads

These bulkheads are brand new. 4 of them are working perfect and 2 have a steady drip. What is going on?

 

They are either not tight enough or they are cracked.

Also did the rubber seal get placed right in the center?

I had cracked my bulkhead when I was plumbing my 75g and it leaked continually.

 

put a little oil on the threads next time before you tighten them down.

 

It's also possible they're too tight. You might know that bulkheads are not meant to be tightened with a tool more than 1/4 of a turn. Once finger tight, another quarter of a turn should compress the rubber sufficiently to prevent leaks. If one tightens beyond this, the compression properties of the rubber are negated by over-flattening, and the seal fails.

 

When I put in a bulkhead, I always put a very thin layer of silicon on each side of the gasket. I second the never tighten them too much.

 

+1 to both comments. I always use a little silicone. Extra insurance. And you should be able to get them tight enough without a tool. Snug and then 1/4 - 1/2 a turn as Sparky said.
If they are leaking you have two options. One, if it's bad enough, your going to have to take it apart and try again. Not too bad, because this should be during a empty FW test, right?
Two would be if you didn't test, and if its slow enough, salt creep may seal it. Otherwise, going to have to drain and re-seal.

 

Bulkhead Basics

Always install bulkhead gaskets clean and dry, no lubricants, sealants, teflon or silicone. DRY.

Always install the dry gasket on the flanged side regardless if its inside or outside the tank. If the bulkhead is a sloppy fit inside the drilled hole, use a small o-ring to fill up the annular space between the inside diameter of the hole and the outside diameter or the bulkhead threads. This prevents side to side movement, centers the bulkhead for a better seal and gives the gasket something to seal against in the void area.

Before you do anything take a couple minutes and using a jewelers file, nail file, Xacto or pocket knife, clean the excess flashing or plastic scrap out of both the male and female threads and from the flange and nut mating surfaces. You would be surprised and how much this one step does as far as preventing leaks.

When installing the PVC plumbing I use and recommend the tread lubricant stick like this:
LA-CO: Product Detail - PLASTO-JOINT STIK® - Plastic Thread Sealant
It is designed specifically for PVC joints and unlike most teflon pastes and dopes it never hardens. It was used in plumbing my swimming pool pumps in 1983 and its still pliable to this day!
You can also find the same thing at Ace hardware or HD and Lowes, often in the natural/propane gas piping section.
I have found over the years the putty type stick is far superior to teflon tapes and pastes. If you feel you must use tape, again go to the natural gas aisle and get the pink or yellow colored tape, its 10x thicker and tear resistant compared to the white stuff.

Hand tighten only with maybe 1/4 turn past that, overtightening is as bad if not worse than undertightening and will leak.

Never support any pumps or major horizontal piping with a bulkhead. It will cause unequal stress on the gasket and leak. Always support your piping and pumps in some other way.

Never fasten piping to the exterior threads on a bulkhead, they are not national standard or tapered pipe threads and will leak. Piping relies on that taper to seal as you tighten.

You will get 100 opinions on which is better, slip or threaded in any combination. Personally I prefer thread x thread as they are more versatile and can be reused. I can't count the times I have helped tear down and move an aquarium where we had to cut the PVC piping apart and trash it since everything was glued. With threaded you can disassemble and reuse the bulkheads and new gaskets are available too.

Clean the threads and mating surfaces
Install the gasket clean and dry on the flange side
Hand tighten and 1/4 turn more
Support and lateral or horizontal piping and pumps, no stress
Use a good sealant/lubricant on the internal threads only

 

All points sound like good practice.

When I installed mine, the LFS guy told me to use silicone grease (if you're a diver, you're familiar with the stuff--it has very similar qualities to vaseline) on the rubber gasket, and that's it.

About a year ago, when I got my drilled 90, I selected the two guys I trusted most (and pretty much still do) on 3reef, sent them a PM, asking exactly how they installed their bulkheads. Their advice most matched what you've written above, AZDesertRat. The rationale from one of them when I asked, "Why not use the silicone grease?" was, "Since it's not in the manufacturer's instructions to do so, if and when the seal fails, you might have some recourse if you follow their instructions to the T. That's exactly what I did--no silicone, no silicone grease.

Good post, AZ. Thanks!

 

I have and use silicone grease for other purposes, mosty to seal the o-rings on my homebrew kegs! (well plus my scuba regulators too)
One problem with lubricants it is causes the gasket to shift or squeeze out when tightening the nut. In a pump or surface with a groove cut for the o-ring to fit into its not a problem. I use it on all my pumps and powerheads when they get reassembled.

Have you ever removed a rubber gasket from something like an old window or windshield where it had dry vulcanized itself to the glass. Thats the effect we are looking for here. The seal doesn't get any better than that.

 

White side of the tank did you put the seal on? Should be on the inside.