Our Expert Answers 12 Frequently Asked Questions About Aquaponics

What Does Aquaponics Mean?

When the word aquaponics first rings through the ear-drums, it can leave behind a trail of questions. That trail can quickly manifest into a stream of inquisitive thoughts that pander on – seemingly infinite. Aqua means water, and ponics means works. Waterworks? Hydro means water too, though. Hydroponics also means waterworks, but what does hydroponics really mean? What’s the difference between aquaponics and hydroponics?

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Aquaponics must be different from hydroponics somehow, but how?

Inquisitive, Thought, Stream of consciousness

Aqua can be tacked in front of all sorts of words and can completely change meaning. Aquatics means water sports, an aquarium is a place to keep fish, but an aquamarine is a stone. When someone thinks of all the weird places that the root word aqua shows up while also managing to represent something completely different, or something only vaguely similar, it can leave them baffled as to what aquaponics really means.

With the right set of knowledge, someone may not take long to connect the dots needed to understand what aquaponics is. Aquaculture is the evasive word that gives a proper understanding of the difference between aquaponics and hydroponics.

aquaculture, aqua-farming, Fish-farm, Aquaponics
Aquaculture or Aqua-farming.

The aqua in aquaponics is actually an abbreviation of the word aquaculture, which is a catch-all word commonly used to explain water-farming. Be it fish, crustaceans, molluscs, aquatic plants, or algae – aquaculture applies to them all.

Aquaponics is the combination of the practise of aquaculture (farming fish) and the practise of hydroponics (growing plants in water).

Any questions? F.A.Q.

Here, let us answer some questions that frequently pop up:

Q: How many fish do I need for an aquaponic system?

A: It depends on if you’re going to grow intensively or not:

  • Intensive growing (high in nitrates) needs very good filtration.
  • The general rule of thumb for determining amount of fish in intensive growing systems is to divide the volume of water by three. 300 gallons of water translates to 100 fish.
  • Less intensive growing (lower nitrates) can depend on your filtration.
  • The general rule of thumb for determining amount of fish in less intensive growing systems is to divide the volume of water by eight. 300 gallons of water translates to 37 fish.

Q: What Kind of fish feed should I use, and where can I get it?

A: We source all of our tilapia feed from a company called EWOS Canada. They make commercially available feed in 20kg bags. Depending on the kind of fish you are raising, there will be different feed. The size of the fish pellets needed is dependent on the size of fish – six millimetres up to one centimetre.

Q: There are lots of different kinds of growing methods to use for aquaponics, which one is best?

A: It depends on the size of your system:

In a hobby scale system, it is best to have a media bed as-well as deep water culture. 

  • Deep water culture is best for maximizing fish health, there is more water in the ecosystem. It also makes the system more resilient to temperature fluctuations.
  • Media beds are ideal for providing extra surface area for bacteria colonies to be established, thus giving more bio-filtration and mineralization.

Q: As far as planning and design, how many square feet of fish tanks for square feet of growing area is required?

A: There are variables, but here are some things to pay attention to:

  • Assuming that your deep water beds are 12 inches deep, you should be raising one pound of fish for every square foot of growing surface. So, If you have a 300 gallon tank with 100 fish at two pounds a fish, then you can have 200 square feet of growing area. This is a good way to determine the total grow bed area in square feet.
  • Another approach: start with a one-to-one ratio of grow bed volume to fish tank volume (300gallons of fish tank to 300 gallons of grow beds. You can increase that ratio up to two-to-one or even three-to-one as the system starts to mature.

Q: How deep should I build a media grow bed? How deep for deep water culture?

A: Media grow beds are generally quite deep, and are filled with some kind of media like clay or gravel. Deep water culture beds are like troughs of water that take rafts filled with seed slowly down a channel of water; growing plants from seed to harvest.

  • For media grow beds, industry standards are about 12 inches deep. This allows a wide variety of plants to grow with better filtration.
Aquaponics, Grow beds, Media beds, Hydroton
An early iteration of our media grow beds.
  • For deep water culture, there should be between four and 12 inches of water; no less than three.
Grow Beds
Deep Water Culture grow beds with rafts of herbs and greens.

Q: How big of a fish tank should I use or build?

A: Typically, the size of a bathtub is the smallest recommended volume to create a stable aquaponic system. You want to avoid temperature fluctuations, and it is typically easier to control the water chemistry i.e. pH and nitrogen levels with a higher water volume.  A 300 gallon fish tank makes it easier to sustain a healthy eco system. You need at least a 50 gallon water volume to raise a fish to 12inches.

Q: How do I design a media grow bed?

A: There are two ways to go about it: flood and drain or constant flow. The general consensus is that flood and drain is better.  As the water drains from the media bed, it pulls oxygen to the bottom of the grow bed, which provides more oxygen to the root zone of the plants.

  • Constant flow is easier to plumb, but it is not very effective.
  • A bell syphon is essential for creating flood and drain system. 

Q: What kind of media should I use?

A: There are a few options, but the best one is an expanded clay product called Hydroton. It is best because it’s inert (pH neutral), it doesn’t decompose,  and it is the right size of aggregate needed to simulate a soil.

  • We use two different sizes of Hydroton and mix them together.
  • If you do choose to use another media, like gravel, make sure that it is inert (pH neutral).

Q: Can I use city water? Or do I need to treat it?

A: When using city water, we suggest that the water is off-gassed before adding it to your system.

  • Off-gassing can be done by letting city water sit for a few days in the greenhouse to optimize temperature and to allow chlorine to escape, or by using a de-chlorination filter.
  • Make sure that when adding water to the system, that both the water temperature, and the pH are close to what the system is at. It is important not to shock your fish!

Q: How do I oxygenate my water?

A: When oxygenating, there are at least three-or-four ways to go about it:

Passive Oxygenation

Forced Oxygenation

  • Aeration pumps use a compressor to add atmospheric air into water.
  • Oxygenation pumps use an O2 bottle to administer pure oxygen into the water. Some oxygenation pumps create their own oxygen using hydrolysis.
  • The most readily available forced oxygenators are aeration pumps that can be found through pentairaes.com/aeration/air-pumps.

Q: How often and how much should I feed my fish?

A: Generally the answer is: listen to your fish.

  • As you get to know your fish, you should be able to tell when they will need to eat.
  • Feed them as much as they can eat in the span of five minutes one-to-three times a day.
  • An adult fish will eat approximately one per cent of its body weight a day.
  • Fish fry (baby fish) will eat as much as seven per cent of its body weight a day.
  • Be careful not to over-feed your fish!
  • If your fish aren’t eating, they may be stressed ( Outside of their optimal pH or temperature ranges), or they could be lacking oxygen.

Q: What kind of plants should I plant?

A: Whatever you want! Avoid plants that need an acidic environment. Cedar trees or blueberries may not be the best.

  • It depends on what fish you are raising.
  • You need to match the temperature range of the fish to the temperature range of the plants.
  • If you are raising warm water fish like tilapia, it is best to companion crop warm weather plants like herbs and a variety of lettuces.
  • If you are raising cold water fish like trout, it is best to companion crop cold weather crops, like spinach, root veggies in media beds, and some vine crops.
Thai Basil
Thai basil growing in our aquaponics system

Still have questions? Book a free consultation or feel free to ask them in the comments below, get ahold of us via social media, or Contact us through our website!

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