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Sunday, September 4, 2011

4 - Installing Bulkheads

Exploded view of Bulkhead Components

You have to do something to let water drain from the grow beds.

If I wanted to just have a simple flood and drain system, I could pump water in the grow bed for a while, then let the water gush or dribble out a hole in the bottom.

But as soon as I want to control that water in any way, I need to install a bulkhead.

The bulkhead I use for the 365 Aquaponics System is constructed from inexpensive PVC pieces you can buy at any hardware store. I use ¾” PVC pipe and fittings. If using metric plumbing bits, the equivalent size is 19 mm.
For some inexplicable reason, plumbing bits in the US are designed with a rounded edge. So for the actual part that penetrates the tank, I use PVC bits designed for electrical conduit.

The male PVC coupling bit is screwed down through the thickness of the tank. Once the coupling is tight, PVC will seat itself against the plastic tank wall in a nearly water-tight fashion. Slip a #18 O-ring around the male threads, then thread the female fitting as tight as you can by hand. The O-ring will make this bulkhead water tight, given that none of these bulkheads needs to withstand more than a foot or 300mm of water pressure.

Credit for this bulkhead concept goes to Richard Kinch, who details this bulkhead design at "An Improvised PVC Bulkhead Fitting for Liquid Storage Tanks."

Here’s a short video clip showing installation of a bulkhead.


  1. All this looks great, Meg,and I am looking forward to setting up my own system next year, using many of you ideas. I do have one small niggle which is this: what you describe as a 'bulkhead' is actually a fitting to go *through* a bulkhead, which is a division in a compartment (like a wall). (Have a look at Wikipedia!) Just to avoid confusion...hope you don't mind.

    1. timx,

      As you may know, I ended up getting tapped to write The Complete Idiot's Guide to Aquaponic Gardening for Penguin Book Group. The book is now available for purchase at It includes lots of DIY plans as well as everything I wished I could have found in a book back when I was starting out (which wasn't very long ago...). So far the reviews are good!

      I used the term bulkhead fitting throughout the book, though I might have slipped a time or two... Even if some people might use the term bulkhead instead, the term bulkhead fitting is always correct! I'll have to review the book and make sure I mark all my slips so it can say bulkhead fitting in case the book gets updated in the future.

  2. Hi timx,

    It's true that bulkhead in naval architecture refers to the water-tight partition. I've walked through and climbed down enough hatches and water-tight doors in ship bulkheads.

    But in aquarium terms, bulkhead is also the term used for the penetration through an otherwise water-tight wall. For example, check out this page of "bulkheads" under plumbing supplies over at

  3. Hi Meg
    I guess that must be a USA usage which I will have to accept - but I will stick by my definition!

    The word bulki meant "cargo" in Old Norse. Sometime in the 15th century sailors and builders in Europe realized that walls within a vessel would prevent cargo from shifting during passage. In shipbuilding, any vertical panel was called a "head". So walls installed abeam (side-to-side) in a vessel's hull were called "bulkheads." Now, the term bulkhead applies to every vertical panel aboard a ship, except for the hull itself.

    You and I are both familiar with this usage, but I guess fish people go their own way!!