Unfortunate turn of events

I was planning a build sprint from Christmas to the end of the contest on my off days for holidays. Did a lot of research, planned everything and gathered all the required materials (covid-19 definitely made that difficult).

But unfortunately my region (Croatia - Sisak/Petrinja)  got hit with few strong earthquakes, the biggest one being 6.4 Richter.

My family is ok, and luckily my house was built strong and 20km away from the epicenter so we didn't have any structural damage.

But many people lost their homes completely and many more had damages on their home. Holes in the roof which leaked because of course it rained the night after the quake.

So my focus now is helping out those unfortunate people as much as I can, and my build is going to wait for some happier times.

Build overview

Here I will write up some details of the build, I will not write about how different aquaponic systems work as there is a lot of info on the web about it.

Research

There are few constraints that we need to follow in order to have a stable aquaponic system and here are conditions for those constraints:

1) How much grow area can we have

2) What will we plant on that area

3) How much does those plant need fertilizers for optimal growth

4) How much do we feed the fish so they produce enough fertilizers

5) How much do we need biofiltration surface area for bacteria colony

6) Required depth of grow beds for specific types of plants

There are few methods, and method below is well researched, free to download and use from https://www.aquaponic.com.au/Aquaponic%20media%20bed%20sizing%20model%20explanation%20-%20metric%20Ver%202.0.pdf

As we are constrained to 1m3 of space sizing up the components was very complicated, and I went through many variations of design and did a lot of calculations.

Decided on the following design:

Ebb and Flow system with clay pebble media beds because they have excellent surface area for biofiltration.. so we don't have to waste additional space for separate biofilters.

To avoid need for the sump tank I divided grow beds in two separate containers one narrow with depth of 30cm (tall plants) and one with depth of 20cm for leafy greens, which will be filled sequentially so there is a minimum fluctuation of water level in fish tank.

Grow beds will be on top of the fish tank and plants will have 90cm of plant area height to grow.

Spreadsheet above shows calculation I made while trying to get the optimal box dimensions. I settled on height>150cm, width>95cm, length>0.7cm which is approximately 1m3 in total.

Width and length of the box can be changed to fit in the space available (this dimensions are a perfect fit for my spaceship ) and everything else is calculated automatically in the spreadsheet.

Height of the box should be at least 150cm to allow plants to grow 80cm I think that is the minimum, you could make it shorter if you plan to grow only leafy greens, but plant diversity and flexibility is better this way.

With these dimensions we are getting 0.6m2 of grow area which need to be supplied with fish waste of approximately 24g of fish, and if we feed them with 2% of their body weight at a recommended fish density of 10kg/m3 we get that we need 122 liters of water for fish.

On top of that we need to add water that will be displaced to grow beds. Both grow beds have the same volume, around 67Liters. They are filled with a media (clay pebbles) which take around 65% of volume and the rest (35%) is filled with water. This percentage can vary a lot so its best to do a media test and measure it to make sure (my media test is in the spreadsheet below). This adds around 24Liters of water to that base 122L, so in total we need to hold a minimum of 146Liters of water in Fish Tank.

I wanted the fish tank to be filled only 80%, so we have a pocket of air on top. At the end Fish tank box of 30cm height was enough. Fish tank will be made of 15mm thick plywood, waterproofed with fish safe epoxy, and two viewing windows. Windows primary use is so Fish behavior can be monitored, but it is also a form of therapy for mental health of astronauts (animal-assisted therapy).

Deep grow bed will go directly on top of the fish tank and shallow grow bed will go on a 10cm riser, which will hold drawers with fish food (4.5kg is required for 6 months), and give access to fish without removing the grow beds.

Grow beds will be waterproofed with pond liner (can also be done with epoxy).

There is a 5cm gap between the grow beds and that is where most of the electronic and plumbing will be placed.

This is how it should look all together:

On top of that is an enclosure for plant grow area 90cm high, which is still not done in the 3d model but its in the excel calculation.

This is the list of plywood plates (WBP stands for waterproof glue), required to make:

FT - Fish tank

D GB - Deep grow bed

S GB - Shallow grow bed

Controller - electronic enclosure

PA - Plant grow area

All of the plywood parts fit on a single standard sheet of plywood for each thickness, at least that is the standard in my country (15mm 3000x1500mm, 3mm 2800x2070).

Most of the shops will provide a cutting service, I advise you to use it. They will do it much faster and precise on their machines than you can with home tools.

There are also calculations for needed m2 of epoxy, paint and liner so we know how much of it do we need (first excel picture)

Build

Here are some pictures of the build process

Used waterproof wood glue and wood screws to build the boxes. Screw holes where pre-drilled so it does not split the layers.

Sanding of the edges is also required.

Fish tank

Grow beds

Final note

That is it from me for now, will do a writeup when happier times come.

I wish everyone good luck with their builds for the contest.

Aquaponics Box: #2 - Hacking the HATs (both HATs from the challenger kit on single RPi)