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Sunday, September 4, 2011

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. I suggest aquaponic growers don't spend money by buying new equipment. The following article clearly states that you can grow fish in hydroponic garden with existing equipment -

    1. Hi Anthony,

      When you posted, I was in the midst of writing 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!

      Again, I agree that someone who already has a lot of hydroponic equipment doesn't need to go out and buy new equipment just to switch over the aquaponics. That said, Dr. Wilson Lennard's PhD research indicates that floating rafts and media beds yield about 20% more than NFT. Plus if you're adding fish, you want to make sure you're adequately filtering the fish water, which may lead you to flood a media bed more frequently than you would in an equivalent hydroponic system. But other than the fish tank, a possible swirl filter, and maybe switching from NFT to floating raft/media bed, there would be no new equipment needed.

  2. You can certainly use hydroponic equipment, if you already have it or if you find it to be less expensive. In my experience hydroponic equipment is relatively pricey and not everyone has easy access to a hydroponic supply outlet. But most people have access to a hardware store.