Building A Gravity Fed Aquaculture System:
This is a guide to building a gravity fed aquaculture system the techniques of which can be applied elsewhere. This is such a huge subject that it really requires a book dedicated to it, so here I will tell you only what we did, but I will also point you in the direction of some great resources.
This particular system uses a passive flow of water redirected from a stream into a fish pond, that then over flows down a number of vegetable terraces, supplying them with nutrient rich water. This system was accomplished on the side of extinct super volcano in the western mountains of Guatemala, in a project known as the Yoga Forest.
In addition to the near vertical angle of the project site, we had the monsoon season to battle with, killer bees, my lack of Spanish language skills. But we also had some very skilled indigenous men, our unbending enthusiasm and lots of humor.
Please meet the core team before I begin
From the left Andre, Francisco, me, Whan or El doctor, Miguel and Eddie.
These guys had to have blind faith in me from the beginning and with my limited Spanish it was hard to explain what I meant. To be honest they didn’t have faith in me at all, they believed the plan wouldn’t work but they new they had to do the work, so they tried their best as always, and made me laugh my ass off along the way.
The site is located beneath high cliffs, you can see how steep the terrain is. The terraces located beneath the cabins have been constructed out of stone found in the river down below. We built them to grow vegetables on but we also new that they would become desiccated very quickly in the dry season and that the top soil was depleted of nutrients due to the heavy rains, so we would need a method of watering the terraces as well as supplying them with nutrients.
So we invented the the Aquaculture System
This image shows the inflow of water from the stream which flows down the ravine and then comes out a pressurized tap into the pond. The tap helps with oxygenation, this function could have also been achieved by pouring the water from a height into the pond. The pond then has an outflow fed by a simple overflow of the water that goes down a pipe alongside the terraces. This pipe then connects to 4 other pipes which have been perforated and drip feed the terraces with nutrient rich pond water.
The pond built on a slope
This image details the pond, the initial concern was that the pond would not retain water without cement or a liner and that the wall holding in the water would collapse either during the monsoon season or just from the pressure of the water inside. But as you can see it holds.
The vegetable terraces in their first season
The system made a marked difference to the quality and quantity of crops we are able to grow.
Where as before most of leafy greens had gone to seed due to stress, they now provide a harvest for much longer.