Need advice on bulkhead installation

[Double J]

I just got a 4 sided overflow box made, with the idea that I wouldn't have to glue it to the tank. I have an acrylic tank. My hang up, is what is the proper way to install the bulkheads? I was thinking of just putting the gasket between the box and tank. Is this right? Thanks for the help, I don't want to find out the hard way!

 

[Drauka99]

gasket goes on the water side of the bulkhead, personally I would buy a few extra gaskets and add one on the overflow box side too

 

[143MPCo]

Quoted from this thread: https://www.reef2reef.com/threads/installing-bulkhead-tips.34973/

Bulkhead tips:

1. Always install bulkheads clean and dry, no silicone, teflon or thread lubricants. Silicone and lubricants cause the gasket to scoot out or not seal properly. Have you ever removed an old automobile windshield or other gasketed glass? The rubber vulcanizes to the glass with time and creates a perfect seal without any help.

2. Before installing the bulkhead take a few minutes using a jewelers file, nail file or pocket knife and clean any excess flashing off both the male and female threads and from the flat gasket mating surfaces of the flange and nut. This is a common source of leaks.

3. Always install the gasket on the flange side of the bulkhead, never on the nut side, regardless if its inside or outside the tank. Installing the gasket next to the nut will lead to leaks as water travels along the threads around the gasket. Hand tighten only with maybe 1/4 to 1/2 turn additional, no more.

4. When using threaded bulkheads, again clean the excess flashing from the threads and valleys and use a stick or crayon type of thread lubricant designed specifically for PVC treads. These can be found at Lowes, HD, Ace and all hardware stores under names like Laco, Permatex and others.

I use this one and have since the 1980's with great success.
LA-CO: Product Detail - PLASTO-JOINT STIK® - Plastic Thread Sealant
It stays pliable forever and does not tear or roll out of the threads like teflon tape. My swimming pool plumbing up to 2" was all installed with this in 1983, outside in Phoenix AZ and its still pliable to this day!
Teflon tape was never designed to be used with PVC. Read this article by LASCO, one of the largest PVC fitting manufacturers in the world:
http://www.lascofittings.com/supportcenter/TheDosandDontsThreadedPlastic.asp

5. Never support any pumps or piping from a bulkhead, always use supports so weight is not on a bulkhead and gasket causing differential stresses on the mating surfaces and leaks.

6. Never screw anything to the external threads of a bulkhead, these are not standard tapered pipe threads (NPT) and will leak. They are there to screw the nut on is all and are not normally even a standard diameter like 1" etc.

Hope you get some use out of this.

 

[AZDesertRat]

If you are using the bulkhead to hold an internal overflow box in place you will need to install the bulkhead with the flange and gasket outside the tank so the water does not travel along the threads and leak oustide the tank. You could then place a gasket between the tank and the box to help seal the box itself but that gasket won't help with the exterior seal.

 

[cromag27]

I've always wondered if that plasto- joint stik stuff was reef safe. I guess it is! thanks.

 

[Double J]

Thanks guys! I had read some of these other posts, just wasn't sure on placement, I may just remove the back from the box and attach it to the tank.
Being they are both acrylic, do I silicone it? Or is there something else I should use?

 

[Double J]

@ AZdesertrat, yes I had planned to use the bulkhead to hold the box. I saw the post about installing the bulkhead with flange to the outside of the tank via gl*****les.com. Question I have is what would you do? Should I just cut the back off the box and "glue" it to the tank? Or go with my first method, if so is one gasket enough or should I put one between tank and box, would it do anything to put 3 on the bulkhead? Ei, nut gasket box gasket tank gasket flange? Sorry for all the questions, first time drilling a tank, my last rr was predrilled and plumbed. Thanks

 

[AZDesertRat]

Acrylic is so easy to work with I would probably use Weld On #4 and solvent weld the box to the tank. As long as you have a good straight cut it will bond good.