Backyard Aquaponics
A place to discuss aquaponics

I finally got some shots from my backyard aquaponics system together!

It is a fluidized gravel bed system with approximately 140 gallons (530 liter) water volume with 60 gallons (230 liters) of 3/8" (.95 cm) pea gravel for media.

The rearing tank is a 110 gallon oval stock tank with a center bottom drain. It currently houses 6 shubunkin goldfish and 1 coy.

The center bottom drain is fitted with an elbow and piped horizintally into a plastic barrel. This barrel houses two pumps and bio-balls and is areated with a pond air pump. The small areation pump constantly runs and leads back to the top of the rearing tank. It has an elbow to give the large tank a slow clockwise rotation. The larger pump is controlled by a timer and floods the Grow bed through a PVC distribution network.

My grow bed is wood framed with a PVC pond liner. It is 4'x4'x8" deep, and is based on the square foot gardening method from Mel Bartholomew. Each of the (16) 1' squares is fed from two sides by the distribution network. The bed takes about 1 minute to fill to the top, activating the two auto siphon drains bulkheaded (ghetto stye) to the front of the growbed. They suck the grow bed down to about 1" of water in less than a minute. The rapid draining action is important because it creates suction and draws oxygen down into the gravel.

At about 1", there is less pressure pushing on the siphons and they reach equilibrium with the pump. The water is still running, but it is acting like a trickle system now. When the pump turns off, the siphons will break leaving about 1/2" in the bottom of the bed. There is about 2" of course lava rock under the gravel to improve flow. The siphons drains create a rapid counter-clockwise vortex in the rearing tank. Pump times are 5 to 15 minutes depending on the time of day. The pump runs every two hours by day, four hours by night with a 6 hour rest period from midnight to 6am.

Current water parameters
PH 8.0
Total Ammonia .5ppm
Nitrites 0
Nitrates 0

Biggest problem right now is temperature stability. I plan to insulate both the rearing tank and the pump tank.

Next biggest problem. Spider mites!! I plan to spray the plants with a capsicum and garlic solution and try not to get it in the water directly! I have to admit that my bio-security sucks in this setup. I sooo wish I had a greenhouse, but you gotta start somewhere!!

Looks like a good start!

A couple things you will probably want to watch.
1- if your grow bed is flooding deep enough that the surface of the gravel gets wet, you could see problems with algae growing on the surface (which isn't such a big deal other than it might look bad and the algae will be steeling nutrients from your more desirable plants) and some plants could have issues with stem and root rot from that. If you find it to be an issue, perhaps you can devise some way to make your grow bed deeper since it looks like you have some excess liner around the edges.
2- buried distribution grids might have a tendency to get blocked up. Sounds like you have a pretty good bio-filter tank going but I don't know how much solids will be going up to the grow bed and could perhaps clog little holes in pipes over time. Probably more of an issue could be plant roots finding their way to those holes and blocking them up.

Don't worry too much though. If it turns out to be an issue, since you are flooding and draining, you don't really need a distribution grid. and could always just disconnect it and let the water flow into the bed in one spot. I've been letting the water flow into my grow beds in just one corner for over a year and it has not been a problem.

Cool thanks for the tips. I knew about the algae, my gavel surface stays dry

It's good to know the nutrients can distribute naturally.

Its not a case of could block up...It will block up.

Looks good otherwise

Onward and upward... good start...

I especially like the padded corners of the overhanging roof

Nice

Yea, I only smacked mt head 4 or 5 times before I added the pads.

The roof was an afterthought, but a good one. Just wish I had made it about a foot taller!

Hi Plantedlab;
Sorry if you've answered these questions elsewhere... but I'm behind on the forum!
Do you know about R&D Aquafarms in Oshkosh? They only sell male tilapia, but they sell small amounts! And maybe then you wouldn't need a permit to import?

We're starting up an AP group here in the twin cities, if you're interested in talking with other 'locals.' http://groups.google.com/group/tcaquaponics The list isn't very active yet, but we're starting to teach classes here. PM me if you'd like more info.