Schedule 40 bulkheads are commonly used in aquaria. Whenever you are installing a new or used reef-ready aquarium, use new bulkheads to save time and avoid frustration.

Purchasing bulkheads is easy when you know what fits and how you want to connect it.  Please look at your options, then select size and style to add to your cart.

Comes in four styles:

Slip / Slip
Threaded / Threaded
Slip / Threaded
Threaded / Slip 
Hole Size for bulkhead:

1" Schedule 40 Black Bulkhead fits a 1 3/4" hole.  The 1" measurement is the inner diameter; it matches 1" plumbing.
1.5" Schedule 40 Black Bulkhead fits a 2 3/8" hole.  The 1.5" measurement is the inner diameter; it matches 1.5" plumbing.
2" Schedule 40 Black Bulkhead fits a 3" hole.  The 2" measurement is the inner diameter; it matches 2" plumbing.
Bulkheads are designed to installed into an aquarium for drainage and to return water back into the display zone.  They are made of Schedule 40 PVC plastic, and come with a gasket. The gasket should be against the smooth flange side on the inside of the aquarium (or overflow box).  The threads on the outside of the bulkhead are to screw on the retaining nut, and this should be tightened by hand only.  

If you are replacing plumbing or moving an aquarium from one location to another, it's usually best to have a new set of bulkheads on hand to start fresh. If you have to install bulkheads in a used tank, thoroughly clean out the area where it will be installed. Any grains of sand, trapped detritus or solids can cause leaks.  The best method to clean out an area is to scrape it clean, then have a helper hold a bucket under the holes beneath the tank, and pour a few gallons of water into the overflow to flush out everything.  Do this twice to assure the glass is completely devoid of solids -- it should look sparkling clean when done.  A new bulkhead installed on a clean surface will not leak.

The bulkheads are inserted into the hole, and the nut is tightened from below. Avoid over-tightening as this can cause aquarium breakage. There is no need to use silicone, paste or teflon tape.  Once firmly snugged tight, it's ready for plumbing. Water test next to look for any drips. 

Please read my tutorial How to install bulkheads correctly prior to installation.