DIY: Mini Aquaponics Set-up

Super excited to grow some herbs in my little 5 gallon aquarium!

Capture
Right now I’m propagating some Tradescantia in the media bed.

growstonFor this set-up I used:

  1. 5 gallon tank – I’ve had this for 4 years, I think. If you don’t already have an aquarium, this DIY may not be for you.
  2. 4 platy fish – I’ve had this breed for 3-2 years. My mom and I forget to feed them sometimes, but the great thing about them is that they eat algae too.
  3. Media bed – I took a perfectly fitting packaging container (it probably used to have baked goods in it) , and cut slits in the bottom and sides.
  4. Media – I bought a huge bag of Growstone Hydroponic Substrate. It’s made of recycled glass, and it’s re-usable.
  5. Aluminum foil – I’m using this to reflect light and slow algae growth.
  6. Tape – No duct tape shame here!… Well maybe a little… Even though the container fitted the size of the aquarium perfectly, I still had a fear of it falling into the tank. I used duct tape to secure it. Next time I’m at my parents house, I’ll try to make it look a little more aesthetically pleasing.

I’ve never used an air pump in this little tank, and my fish have always been happy. Roots require oxygen for aerobic respiration, as well as the fish. Oxygen deficient roots are less permeable to water and accumulate toxins. This results in insufficient absorption of water and minerals to support plant growth. The warmer the nutrient solution is and the higher the ppm of dissolved solids, the lower the dissolved oxygen content in the water and the higher rate of respiration.

DSCN1627

The key to providing leafy greens optimal oxygen without using an air pumps is to only submerge the tips of the root mass (about 2 cm above the ends). This allows the water to wick through the rock, while providing ample air for roots.


results4
The four hydroponic treatments.

I did a research experiment in college called “Crop Yield, Growth Rate, and Root Mass in Hydroponic Treatments of High Dissolved Oxygen Concentration Vs. High Fertilizer Concentration” (such a mouthful)… There were four hydroponic treatments in the experiment. Of the four treatments, two treatment’s nutrient solutions were aerated every day (with a 40 gallon air pump) and two were not. The nutrient solutions were maintained at about 2 cm above the root ends. There were also two fertilizer treatments (but I won’t discuss those because they’re not applicable here).

Cutting right to the results…

results
Average total leaf area over time as a function of fertilizer and aeration treatments. (“AP” means air pump, “x” means the recommended fertilizer concentration, and “x/2” is half the recommended rate.)

There was no significant difference between aerated (AP) and non-aerated lettuce. Growth seemed to be more limited by nutrition (x and x/2) than by dissolved oxygen. Therefore, I’m planning on not using aeration. We’ll just see how that works out.


I’m looking forward to learning more about aquaponics. I hope to build a large system in the future. Let me know if you have any advice, or know of any good aquaponic resources!

Hope you enjoyed!

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