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How To Grow Vegetables With Aquaponics *

If you’re interested in starting a small garden with a minimal carbon footprint, aquaponics is a great method to try. Compared to normal gardens, aquaponics systems use less water, generate less waste, and yield just as much produce.

Nitrification is at the heart of aquaponics. Essentially, it boils down to converting the organic matter in fish tanks into nutrients for the plants. The chemistry behind it may seem complicated but starting an aquaponics system is as easy as following these five steps!

1. Invest in Reliable Equipment

  • Aquarium: First and foremost, you will want a 100-gallon aquarium as the base of your aquaponics system. Depending on whether you buy a glass or acrylic tank, it will cost $200-$400 for a rectangular tank. While it is more expensive than smaller tanks, the 100-gallon tank is best for aquaponics because it gives you more options for the types and number of fish and plants your system will support.
  • Filtration system: Every tank needs a filtration system, but not just any will do. For a 100-gallon tank, look for a high-power external or canister filter. Anything less powerful than these will not keep your tank clean.
  • Air pump: An air pump ensures stable oxygen levels for the fish and plants. You can also use it to push water through a filter. Usually, a canister filter will stabilize oxygen levels, but some setups may require an air pump for filtering.

Tubing for irrigation will be needed for the media bed setup and nutrient film setup discussed below. Water heaters and grow lights are options, but whether you need them or not will depend on your specific setup and goals.


2. Choose Your Setup

  • Media bed setup: Media bed setups are the easiest setup to use. The media bed is usually created from pebbles, gravel, or lava rocks. This layer sits at the top of the fish tank or next to it, and a pump carries water from the tank into the media bed. The plants filter out the nutrients they need from the water, which is then pumped back into the tank. It is best to build the media bed yourself. You can use this guide from the Southern Regional Aquaculture Center as a reference.
  • Nutrient film setup: A nutrient film setup requires a PVC tube with holes drilled into it. The plants are positioned such that their roots dangle inside the tube. Then, the water passes from the tank into the tube, then back into the tank. This method is great for those who have limited ground space because the tubes can be attached to the wall. This setup can be built easily or purchased from Amazon.
  • Raft setup: Raft setups are more popular for commercial operations but can be used small-scale. To create a raft setup, plants are placed on a foam raft such that the roots hang into running water that is drawn from the fish tank. This method has a high yield but requires extensive filtering.
The fish fertilize the plants and the plants clean the water for the fish in an aquaponic system. Image credit: GRACE Communications Foundation and Mother Jones, CC0, via Wikimedia Commons

3. Add the Fish

An aquaponics system will support many species of fish. Two of the most popular options are:

  • Tilapia: Tilapia are used frequently because they are durable and adaptive. They will tolerate temperature changes, pH shifts, and high ammonia without dying, and as a bonus they are inexpensive.
  • Koi: Adding koi to an aquaponics system will make it aesthetically pleasing without breaking your budget. A caveat is that they are susceptible to many ailments; however, they can tolerate very poor water quality and still do well.

These are great options, but you can also consider carp, perch, largemouth bass, bluegills, guppies, and more. Be sure to purchase your fish from a reputable seller to ensure they are healthy.

4. Add the Plants

Like fish, the options are endless when deciding which vegetables to grow in your aquaponics system. Some popular options include broccoli, celery, cucumbers, and basil.

But because different plants require different conditions, you’ll want to select plants that will thrive in your setup. As Go Green Aquaponics explains, it is important to consider the following:

  1. System: What type of aquaponics system you will use – plants with no root structure do well in a raft setup, while root vegetables do well in a media bed.
  2. The optimal temperature and pH level for your fish and your plants – the closer the match, the more successful you’ll be.
  3. Environment: the amount of light, temperature and – if you’re setting up your system outside – rain the plants will get.
  4. How much space you have for plants versus how much space the plants need to grow.
  5. Plant-to-fish ratio: The more fish you plan on having, the more plants you need to absorb the nutrients.

5. Maintain Your System

Keeping healthy plants and fish will require regular maintenance. Some tips include:

  • Feed your fish two or three times daily, but be careful not to feed them too much, as this can affect the water quality.
  • Check the pH levels weekly or biweekly. To test the pH, use a test kit like this one from API. For this kit, add aquarium water to the provided tube, put three drops of the test solution in the water, then compare the color to the reference card to determine the pH. (Other kits may provide different testing materials, and will therefore have different instructions.) The pH level should be between 6.4 and 7.4, but most systems naturally drop lower. To raise the pH naturally, try dissolving a spoonful of potash or hydrated lime into a bucket of water, then add it into the tank. Wait 24 hours and test the pH again before adding more
  • Check ammonia levels and nitrate levels of the water weekly or biweekly. In a healthy system, the ammonia and nitrate levels should be undetectable – ammonia levels should be less than 2 ppm, while nitrates should be no higher than 160 ppm. To check the ammonia and nitrate levels in your tank, use a kit like this one. This kit is very similar to the pH kit, so it will be easy to use. If the ammonia levels are too high, feed the fish less, reduce the number of fish, or increase the aeration in the tank. If the levels are too low, do the opposite: Feed the fish more or add more fish. If nitrate levels are too high, add plants or remove fish.

Summary

Aquaponics is an easy and environmentally conscious way to grow produce and raise fish at the same time. It can be used to grow all your favorite leafy greens, and there are endless varieties of fish that will adapt well to this system. Just keep up with regular maintenance and aquaponics will prove to be a viable and sustainable new way to garden.

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