Aquaponics experiment 2013 week #2: support structure built, grow beds installed and pump upgrade

Posted on May 25, 2013 in DIY

Fabricating the grow beds from a 55 gallon barrel

I cut a single 55 gallon plastic barrel in half to create two grow beds. I was lucky enough to score two of these white barrels from a couple of friends, and was pleasantly surprised to find that they were completely clean on the inside! A circular saw made short work of the barrel, and an angle grinder was used to deburr all the edges.

I put a single hole near the bottom of one end of each barrel halves to make space for some bulkhead fittings, which will allow the water to be drained through a loop siphon in the completed system.

Building a wooden support structure for the grow beds

To hold the two grow beds, I whipped together a wooden support structure just wide enough to hold the barrels. However, once I loaded one barrel with gravel I realized that the spacing of wood supports was a little too much, allowing the barrel to distort and slump down way too much for my comfort. The bottom of the barrel was actually resting on the fish tank!

Adding additional supports to the structure

I used some spare 2×4 scraps to reduce the width of the support structure and support the barrels a little better. After doing this, a fully loaded barrel no longer sags all the way to the fish tank.

Rigging up the pump to the grow beds

Next was the seemingly simple matter of connecting the pump to some tubing to actually fill the grow beds with water from the fish tank. Since I didn’t see an easy way to connect the pump’s outlet to solid PVC, I opted instead to use flexible 1/2″ black tubing. It goes straight up from the pump and into a tee junction insert, then out to both of the beds.

At first I was having problems getting the water to flow equally into both grow beds at the same time, but after asking around online it turned out to be a really simple fix. If there is any sort of downward slope to one of the tubes, the water will tend to favor that side over the other. To fix this, I just drilled a line of holes into the top rim of each grow bed and used twine to secure both outlet lines nice and straight and even with each other.

Earlier this week I was having problems with the pump; it would just shut up randomly. It still made a whirring noise, but the impeller wouldn’t spin. I brought it home and found out that I could try to poke the impeller with a screwdriver to get it going. It worked like a charm, but the next day the pump would keep shutting off over and over again. I decided it would be worth the investment to upgrade to a more powerful pump, just in case.

I picked up a 396 gallon per hour pump, which should be a pretty dramatic difference from the 185 gallon per hour one I’ve been using until now.

Washing the gravel – day one

The last thing to do before getting bacteria going and stocking the fish tank is to wash the gravel. You wouldn’t believe how dirty the gravel I picked up was; it is completely covered in mud! I’ve heard of people doing all sorts of things to wash their gravel, all of which sounded pretty time-consuming and labor-intensive. Then I heard that some people don’t wash their gravel at all! I figured I”d strike a happy medium and wash the gravel a little bit as I add it to the grow beds, and pitch all of the dirty water as it comes out of the siphons.

I got one bed’s worth of gravel washed pretty good, but by Friday I was frankly just a little tired of fussing with this project, so I took a break. On Monday I’ll finish washing gravel and install my new pump, hopefully to be ready for 5 channel catfish that will be arriving on Tuesday afternoon!