|Side view - High density marron farm idea|
The water and solid fish waste would flow from the fishtank into a flow splitter made from an 8 inch PVC pipe connected at right angles. The flow splitter would then be connected to a number of 8 inch PVC pipes that would slowly take the flow to the growbed.
Each PVC pipe would contain a number of different baskets that could move freely along the PVC pipes.
Each basket would hold one marron. The largest marron would be those closest to the fish tank, and these would get first bite at solid fish waste, and uneaten food. As the feed and solid waste moves to the right, the other, progressively smaller marron get a chance at it. Mature marron would be harvested from the end closest to the fishtank, and new small marron would be added to the system at the growbed end. Each marron would be in a separate basket to prevent fighting.
The water would enter, and move through the system via gaps at the bottom of the baskets. To maintain water in the pipes, the water would exit the pipes at the top.
|Top down view - High density marron farm idea|
Seen here from the top, we see the flow rate from the fish tank would be very slow because of the large diameter of all the PVC pipes. This would give the marron several chances to catch passing food. The total flow through the system is the same as it would be without the marron farm, but because it's spread over such large pipes, the flow slows.
The length of the marron farm pipes would depend on how many marron your system could support.
Using this or a similar system it should be possible to grow marron (or whatever underwater walking things are called in your part of the world), in an aquaponics system without all the cannibalism that can come with underwater walking thing farming. This marron farm would be placed in the following order of flow...
- fish tank
- marron farm
- swirl filter
- grow bed
Small marron might be kept in an aquarium, and only the largest of the batch might be added to the farm each week. Grading out only the biggest marron might prove difficult so I might have to come up with a way to trap the biggest and let the others through unhindered.
I'm not sure if this is the solution for me. It's just an idea that was rattling around in my head, so it had to come out.