The Finished Product
Here we got the beds running well. The basis of the system is to have a modular system that is easily expandable to cater for any size family needs. The depth of the bed is 300mm which is a constant, the plastic supplier supplies sheets that are 1m by 2m so it take two sheets to make one grow bed.
This is significantly cheaper than getting one made from fiber glass. Where we stay it is not readily available and must be brought in from the nearest city which is 3 1/2 hours of driving away. Fortunately the company delivers every week so I have no problems sourcing material from them. The frame is welded together and painted. I've only made four frames to date but will make two more in the future. Aquaponics gives you the ability to grow a lot of plants in a very small area. This is great for getting productivity out of a small area, but is horrible if you need to control things. Roots get tangled often when they search for nutrients.
Final Frame
This is the final frame design for now at least. It has a support for my swirl filter which will be explained later. By the time I got to this frame, I had most of the manufacture kinks sorted out and it works well.
Compared to many I know I've not chosen the easiest or the most recyclable technique. I needed to have a portable system at the time so this was the product.
Buckets of Fun
Here's the inside view of the grow bed. I welded in black to show it up easily. I must say at this point, that I prefer to use black for the grow beds as they take the sun much better than white and white plastic allows algae to grow on the inside as many IBC users have found out.
Welding plastic is a skill that can be learned and the more you try, the better you get. My advice if you try this is make sure you know how to work safely and get help. You always need help to move chords or things out of the way. Once you start a weld, you only get to stop when you're finished.
Things to balance are the pressure with which you feed material in through the welding nozzle and the speed you travel along the weld. The weld is weak if you go too fast or press too weak. If you go too slow you melt it too much and you can't fuse the plastic in the weld. Too hard and your hands want to fall off soon.
These grow beds have a volume of 600 liters and when filled with 19mm stones it has a cavity area of 200 liters and 400 liters is taken up by stone. I haven't measured it exactly, but by watching changes in my sump tank it is about right. To make the system work you need a bell siphon and here's my design. It's real cheap and all in all costs about the same as coffee in a coffee shop.
So here are all the parts for the stand pipe in the middle. First notice the very short piece of pipe on the very left. It's not short but actually welded into the bottom of the grow bed, it stick out about 120mm below. I don't use bulk head fittings and this is leak proof and doesn't need silicon sealer.
Here the stand pipe is fitted together and ready to push into the down pipe. By changing the height of the standpipe, you change the maximum height of water in the grow bed, I don't, but you can if you want.
Left to right, the stand pipe is fitted into position, the bell is fitted over it and the shroud which is made from 104mm sewerage piping is fitted around the lot before filling up with stones. If you are using stone crush like me you hold the shroud in place and fill stones around it. By the time it is 300mm deep you can let go and it will stay in place. If you use round pebbles or clay balls, you need to keep it in place with a brick for a while till it all settles nicely.

















