The system I built is from the Endless Food Systems DIY plans. I used untreated pine for all my grow beds, and treated pine for the sump tanks that will sit on the ground, as well as the leg supports. To line the beds, I did a lot of research, and settled on DuraSkrim pond liner. It’s what aquaponics farmers use to get organic certification. I was overly concerned with using plastics and how the leaching could impact the quality of the plants. It’s really hard to get away from plastic, since galvanized metal is poisonous to fish. Unless you have the time to let algae coat all the surfaces, the zinc will be toxic. I emailed a friend of mine in the plastics industry, who happens to have a lot of the same concerns I do, and she recommended I go with the DuraSkrim. I ordered a roll online, but realized later that my local aquaponics store (Brite Ideas in Austin) carries it as well. I could have saved so much on shipping!
For the plumbing, I chose to use polyethelyne pipe (aka pe pipe) for the main units. PVC has a bad reputation for good reason. You can have leaching at high temperatures, and the chemicals used in their construction are still controversial. PE pipe has a much higher temperature threshold, and generally speaking has a better reputation. I like that the parts all snap together without having to use toxic glues, and are easy to cut and assemble. As someone with virtually no plumbing experience, I appreciated it! I tried to use 2″ PE pipe to connect my sump tanks, but I couldn’t find the fittings I needed nor figure out how to get the tools to connect them. So, we went ahead with PVC for the sumps. I’m not entirely thrilled about it, but it will do. I’m pleased to say I also did this myself! Hopefully I didn’t lose too many brain cells in the process 😉
Choosing the media to fill my beds was an obstacle. At first, I planned to only have media in my main grow bed to act as a filter for two raft beds. But talking to a few pros and attending some classes led me to decide to go with media in all three beds. It seems rafts are best for leafy greens only, and if you want fruits or vegetables you need something a bit more sturdy for them. I talked to a lot of folks about different options, and it seemed that granite would be the most affordable and easily available option. At least, so I thought. My dad mentioned he had several cubic yards of decomposed granite on the property that I was free to use. And that was the key word, FREE! I was so thrilled. I set out sifting and rinsing all the dirt, piling it into a tub and filling up my first bed. It took me four hours and something like 200 shovels worth of granite. All to find out that it was too small. Oy. I posted a photo along with a question to the Facebook aquaponics group I’m in, and the consensus was that the rocks were too small to work well as a media bed. Ouch. So I set to work emptying the bed. The good news was it only took 30 minutes. The bad news was my entire body ached to high heaven.
I was told to look for 3/4″ granite rocks, and to make sure to do the vinegar test to check for pH neutrality. Basically you drop a few stones into a jar of vinegar, and if it fizzes, you don’t use it. Luckily this passed. I searched for a couple of weeks to find a stone yard that carried the size granite I needed. Finally, I found it at New Braunfels Mulch. They had 3/4″ – 2″ granite for $55 a cubic yard, and offered delivery. I ordered two yards, and it turned out to be exactly enough for my three beds! Considering bags of the stuff at box stores run $6 per half cubic foot (meaning I needed about 100 bags) I consider it a great bargain.
The rough part was rinsing and moving, but I managed. I’m thinking I’ll start a new diet program: Body by Aquaponics! I drilled large holes in the bottom of a five gallon bucket, put in 5-6 shovels of rock, rinsed it then dumped it. Registration offices Several hundreds of buckets later, my beds were filled. Whew! Now I just need to finish up the leak checking, bribe my husband to finish wiring the electrical, and it’s time to fill up the beds! SO CLOSE NOW!