Week 21: Plastiponics

Yeah. So, I’m in the Bahamas. Life is tough sometimes. I have been here for about 9 days and I already feel like I’ve been here for a year. I don’t even think I realize how much I am learning each day. My internship here is focused on aquaponics. In a nutshell, aquaponics is a synergistic recirculating system between (in this case) aquaculture of Nile tilapia, Oreochromis niloticus and the hydro culture of leafy greens & herbs. We’ve got 6 different stages of tilapia from little fry to 3-5 pounders as well as a brood stock, or as I like to call it: Big Mamas tank. We’ve got a settling basin, biofilter, and 10 grow beds.

Aquaponics has been around since the beginning of time, but modern aquaponics is quite possibly impossible without…wait for it…wait for it…PLASTIC. So, I’ll walk you through the system as best I can. Keep in mind that I am not an aquarist/culturist by training, or a plumber, or a biologist. So, forgive any mistakes. I’m doing this all from memory as I am in the lab right now AND I’ve only been here a week! That’s what the “comment” component of a blog is all about. I would love to get a holler from NEAq aquarists out there for some edits if you see any!

1. Let’s start with tilapia eggs. When it’s time for the Big Mama tank to get some action, a few #2 plastic fuel jugs (cut in half) are placed in the fiberglass tank. We drop a couple of males in, magic happens, cut to eggs.
2. Since tilapia are mouth brooders (keeping the eggs in her mouth), there is a plastic device like nothing I’ve ever seen before to “assist” in gently getting the mama to cough up the goods, as it were. I’m not sure what this egg extruder device is made of, but my best guess would be Plexiglas with some combination of HDPE & PVC.
3. Skip to fry. So, we have a little nursery of infants, toddlers, tweens, & teens. The infants, toddlers & tweens share a fiberglass tank rigged with 2 plastic dividers, creating 3 tanks in one; each section being rigged with a removable “tray” made of polypropylene netting & PVC.
4. In the adult fiberglass tanks, there is PP netting spread over the tanks (they’re jumpers!)
5. The settling basin (aka, poop homestead), where a lot of the solids from the fish settle is covered with a heavy-duty tarp (not sure what kind of plastic) and tied down with PP rope. This is to keep algae from taking over & pigging out on all the oxygen.
6. The biofilter is filled with this mystery plastic ribbon, which provides surface area for other solids to bail out before entering the grow beds. I want to find out what kind of plastic this is…
7. Then off we go (about 15 feet of PVC later) to the grow beds. Behold—the miracle of growing plants without soil. Our Genovese basil, Speckled Amish Bibb and Jericho lettuces come into this world surrounded by a growth medium (rockwool or coir) in little black plastic seed pots.
8. These little black pots are then placed in large HDPE bread trays and watered daily via a plastic watering can or plastic-coated hose.
9. After a couple of weeks, the pots are placed in one of the hundreds of holes carved out in one of the 30 polystyrene rafts floating in the plastic-lined grow beds.
10. All of these tanks and beds are oxygenated with the help of clear tubing (LDPE, me thinks) and air stones. Does anyone know off hand, the material of the “stone”?
11. All of the tanks & beds have in flow & outflow PVC pipes.
12. And it goes without saying that this program was brought to you today by our sponsor, PVC pipes unlimited. PVC IS the circulatory system of aquaponics. PVC: the necessary evil.

And there you have it. With our 12-step program, you too can have your own aquaponics system. Stay tuned for next week’s posting about CEI’s zero waste initiative! I’m hoping to have some photos of that as well as the aquaponics system up soon.

I never thought I would say this, but…I kind of miss my tidy little plastic pile (errr...not to mention my family & friends!) Since I have been here, I have only collected a handful of plastic items. Living in community…definitely a good cure for the “single serve” mentality in which I usually find myself.

Under this star-littered Bahamian sky in the little town of Cape Eleuthera, I bid you farewell until the next post.