Thursday, April 3, 2014

Fish Garden Version 2.0

So last year I built a small aquaponic garden in my back yard, it worked alright but had all the looks of a prototype and my lack of experience shown through.

you can almost hear it asking me why it must suffer
It was a great proof of concept but it had some flaws. The beds are made up of two 55 gallon barrels cut in half with a third serving as a fish tank, the system fed into the beds by gravity. The beds then drained into the sump with a bell siphon which were then pumped back into the fish tank. The base you see there was actually two cheap raised beds kits from Home Depot stacked on top of each other, the sump is two large plastic storage containers connected together with ¾ inch pipe.

There were a few problems with this design, first we had no access under the beds, so once we filled them with our grow media (red lava rock) we had no way to get under the system to fix something or make changes. Second once rock was in the beds the ends sagged down with the weight, we ended up having to prop supports under them to get them close to level. Third was the siphon which worked but managed to keep pace with the pump (rather than passing it) which meant the beds would drain down and overflow the sump, I lost a lot of water that way.

So a couple weekends ago I (with some help) rebuilt the system, the beds and fish tank and  sump stayed but the Frame went away.

This is not even my final form!
The first obvious improvement is the frame, which along with being taller (36 inches to the top of the corner posts), holds the beds much more level, and allows access underneath. When I built the first garden I rather naively thought I would be able to get two siphons to work in tandem, now I use the plumbing from one to pump water into the beds, which the siphon through the bed at the other end. Speaking of Siphons, the added height along with a pipe below it mean a much stronger siphon meaning the beds drain down much more quickly. I added a fall pipe to make the siphon stronger, the pipe had holes drilled near the bottom which introduce air into the water.

Also I've decided gravity just doesn't work for the system, and added a fill pump to the system. The system cycles much more regularly and I’m rather pleased with it I bought a timer which I intend to use to stretch out the dry time in the beds. My next step will be to plumb the overflow from the fish tank (which has turned into where I’m losing water) back into the sumps to keep water in the system.

I'm still not done with this experiment, cosmetically I’m going to cover the front and two sides of the garden in lattice to hide the inner workings and make it more attractive. On the technical side I’m going to use an Arduino and prototype an automation system for the garden. I want it to shut off the fill pump when the beds start draining and to give me more control over how long it waits to start filling again. Later I want to add sensors for water temp, dissolved oxygen, ph, and fish tank water level. Once things are dialed in with the Arduino I may try flashing my own microcontroller and putting everything on a single homemade board, but that is a ways off for now.