Aquaponics FAQs

aquaponics.png AQUAPONICS AND CNG 

What is “aquaponics”?

Aquaponics combines raising fish and plants together in a symbiotic, recirculating system. In Aquaponics, natural bacterial cycles convert fish waste into nutrients that the plants can absorb, which in turn cleans the water for the fish. The word comes from combining aquaculture (raising fish or other aquatic animals) and hydroponics (growing plants in nutrient-rich water).

What are the benefits of aquaponics?

  • It uses 90% less water than soil-based farming
  • It can produce fresh, local produce and fish year-round
  • It produces food reliably without the use of synthetic chemicals.
  • Local food can be produced in places where soil-based farming is extremely difficult or unwise, such as where there is drought, soil contamination, or high-density urban spaces.

Why should CNG offer certification for aquaponics?

Interest in aquaponics is surging. Both producers and consumers would benefit from a certification program that provides an incentive and recognition for aquaponics producers who use the most sustainable practices possible. Certified Naturally Grown offers transparency by making each producer’s application publicly available online. Furthermore, the peer-inspection process is a way for producers to network, learn, and share knowledge on best practices.

Doesn’t aquaponics require a lot more plastic than traditional soil-based farms?

Many of the components in aquaponics systems are plastic. However, they are generally reusable and have a long useful life. Soil-based farms also routinely rely on a lot of plastic products (pots, landscape fabric or mulch, drip tape, irrigation pipe, twine), which tend to have a relatively short useful life and are discarded annually, or bi-annually.

Why don't you certify hydroponic operations?

We discovered that there are very few commercially viable hydroponic operations that rely on natural fertility sources. While we have heard from a few hydroponic producers who are confident it can be done, at this time the number and track record of such producers is too small to justify developing a whole new certification program. If you grow hydroponically and think we should reconsider, please tell us about it here.

When do you expect to start taking applications from aquaponics producers? 

We have launched the program and are currently accepting applications for CNG aquaponic certification. 

Where can I find Certified Naturally Grown aquaponics operations? 

After we begin to accept applications from aquaponics producers, those that are accepted into the program will be listed on our website at Visitors can see a listing of all CNG producers in a particular state, or search for aquaponics producers within a given radius from their town or zip code. 


Are compressed grow plugs or rock wool allowed?

They are allowed as long as they don't contain synthetic fertilizers. These are products where fibers (peat or coir in the case of most grow plugs, and mineral fibers in the case of rock wool) are compressed and held together with binding materials. The structure provides a porous growing medium that provides structural support to plant roots while allowing the right mix of air and water to reach the roots.  Certified Naturally Grown views these products as essentially serving the same function that plastic pots serve on soil-based farms.

What pH adjustment products are allowed?

Minimally processed forms of calcium carbonate are allowed such as dolomitic lime and oyster shell flour. However, most pH buffering materials are synthetic, and at this time most producers consider them necessary to achieve a steady and balanced pH without causing stress for fish and the system as a whole. CNG allows these synthetic materials (such as calcium hydroxide, potassium hydroxide, and others), at least until further developments in the field of aquaponics yields a more natural alternative.

Do you allow soil, compost, or vermicompost in aquaponics systems? 

In response to public comments, we updated the standards to allow for soil, compost, and vermicompost to be used in dead-end or non-recirculating sections of the system. These materials are natural, non-synthetic sources of nutrients. Many aquaponics systems function perfectly well without the use of these materials, but some producers find soil, compost, and vermicompost useful. CNG's revised AP standards will allow their use in CNG operations, as long as the water does not recirculate from the portion of the system where those materials are used. 

Do you allow the use of IBC totes?

In response to public comments, we made some changes to the draft standards. It is prohibited for IBC totes to be brought into an already CNG-certified operation. However, recognizing that many start-ups use IBC totes, the revised standards will allow IBC totes to be grandfathered in to CNG operations, but ONLY IF a) they were in use by that operation prior to certification, and b) they were either purchased new or it can be verified that they were only used for food-grade purposes prior to use by the aquaponics operation. It is expected that the grandfathered IBC totes will eventually be replaced. CNG has prohibited the introduction of IBC totes to a CNG aquaponics operation because they are designed for a one-way trip, not continuous use, so they are subject to degradation - just like water bottles and milk jugs - and shouldn't be relied upon for long-term use in a commercial aquaponics operation where food is being produced for sale to others.  

Why is recycled plastic not allowed?

Recycled plastics present an increased rate of degradation and risk of leaching compared to virgin plastic, and additional risks posed by chemicals that may be added to plastics shipped overseas for recycling.

Why do you allow but discourage vinyl? And EPDM?

We are aware of concerns about off gassing and leaching, but there isn’t conclusive scientific evidence that would justify prohibiting them. These materials may be prohibited in the future, pending more evidence.  


Are the plants, the fish, or both certified? Why?

Just the plants will be CNG certified. There is only a very small supply of fish feed that would meet CNG standards for livestock certification, and that supply of organic fish feed doesn’t contain fish meal, an ingredient which professional producers consider essential to ensure palatability. That and other features of aquaponic fish management lead to the decision to postpone CNG certification for aquaponic fish until a later date.

Does CNG define any standards relating to fish feed?

We encourage producers to use feed that is organically grown, and feed that does not contain primary catch. However, because the organic fish feed market is in its early stages, there is limited availability and an extremely high cost barrier. Therefore we do not require that fish feed be organic, and we will not offer CNG certification for the fish raised in a CNG operation. As organic fish feed becomes more available, we will revisit CNG fish feed standards. CNG draft standards prohibit fish feed that contains (or is) medications, hormones, or human or other animal waste.

You require producers employ practices that prevent fish disease. What factors impact fish health?

Factors impacting fish health include the following: handling, transport, and harvesting practices; temperature, pH, light levels and stocking densities; feed type and quantity; water quality, filtration and dissolved oxygen; biosecurity and hygiene.


Who decides whether the producer’s system is “designed to adequately to perform certain functions that are critical to the overall health of an aquaponic system” (e.g., bio filtration, removal of fish waste solids, water circulation, aeration, degassing), and why aren’t these standards more specific?

Since Certified Naturally Grown does not require any particular design or kind of system, it is not possible to set very specific standards for assessing whether a system is performing functions critical to the overall health of the system. There are just too many variables. However, CNG does require Producers to ensure that their aquaponic system is designed to adequately perform these essential functions. In the application process, producers will be required to describe in their own words how their system is designed to perform these functions.  A preliminary assessment will be based on the answers they provide initially, and in subsequent correspondence. Further assessment will be made by the inspector during an on-site review. During this review, recommendations may be made for system improvement. Indeed, this is one of the benefits of our peer-review system! But, if there is disagreement between producer and inspector about what is adequate, the case may be taken up by CNG’s Aquaponics Advisory Council, if there isn’t precedent, or by CNG staff, if the Council has already addressed the particular question.

Who will conduct inspections? Are you hiring inspectors?

Certified Naturally Grown is a Participatory Guarantee System, or “PGS”, and as such relies on peer reviews instead of third-party inspections. We do not hire inspectors. With CNG, it’s other producers, typically ones who are Certified Naturally Grown, who conduct the inspections. Inspectors might also be certified organic or non-certified aquaponic producers using natural methods. For full details on inspector options, see section 12 of the Aquaponics Standards. All certification reports are posted to each CNG producer’s profile, along with the inspector’s name, farm name, and signature. All CNG producers agree to conduct an inspection of another CNG producer if there is one within an hour’s drive who needs an inspection. Peer inspections are done by unpaid fellow producers.

Learn more about PGS, an internationally recognized grassroots approach to certification, at