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Aquaponics & Cannabis: 3 Major Obstacles

In order to get high yields with aquaponics, a cannabis grower needs to familiarize themselves with the basics of how an aquaponic system works. To grow cannabis successfully in aquaponics, the system must be configured to produce the high levels of nutrients needed by a plant like marijuana, and that takes a little extra know-how!

Aquaponics is the art of combining aquaculture (growing fish in tanks) with hydroponics (growing plants in water). It’s sort of like organic hydroponics!

In an aquaponic growing system, fish are raised in a tank and the nutrients they produce (contained in their poop and produced by their gills) gets converted by bacteria into nutrients for the plants. The plant roots help clean the water before it is re-circulated back to the fish tank, completing the cycle.

Aquaponics creates a tiny ecosystem – fish make nutrients for cannabis while cannabis cleans the water for the fish!

Although fish are the most common species used for aquaponics, other aquatic creatures like shrimp, crayfish or prawns can also be used. Both edible fish and ornamental fish can be used successfully in an aquaponic system. Generally you want to pick a species that is hardy and can tolerate crowding. Tilapia is an edible fish that adapt very well to aquaponics, and koi or goldfish are great choices for ornamental fish since they are nice to look at and can thrive in sub-optimal environments.

Aquaponics may be the most efficient way there is to cultivate both fish and plants at the same time because combining them together reduces the cost of farming each one individually! In big commercial operations, aquaponics is used to produce profitable combinations like tilapia fish and lettuce. In smaller setups, aquaponics is a sustainable, low-technology and efficient way to create food even with infertile land and low resources – aquaponics dramatically reduces the amount of water needed for raising fish, while producing high-nutrient plants at the same time!

You feed the fish, they feed the cannabis!

When it comes to growing cannabis in aquaponics, one of the big goals is to set up a system that produces high levels of available nutrients. Growing cannabis plants gobble up nutrients, especially in the flowering stage, so you need to ramp up an aquaponics system to optimize it for high nutrient output! That means that you need to make sure you have a high density of fish, as well as a really great bacterial colony to convert all that fish poop into nutrients for your plants!

Life Cycle Inside a Cannabis Aquaponics System


The Rearing Tank / Aquarium is where the fish or other aquatic creatures live. These creatures produce waste containing nutrients that are vital for plant growth. Common fish used in aquaponics include tilapia, koi and goldfish, but there are many other hardy species that can adapt to an aquaponic environment including blue gill and catfish.


Your system will have a Hydroponic Sub-System, which is basically the tank or reservoir where cannabis plants grow with their roots in the water. In many ways, you grow your cannabis plants in aquaponics just like you would with a traditional DWC/hydro setup. The main difference is the fish produce nutrients instead of you having to add them!


Bacteria make up your Biofilter, the “heart” of your aquaponics system. The bacteria biofilter is the missing piece that allows you to run a symbiotic relationship between the fish and the plants like in nature. When you create a nice home for the bacteria, they work hard to convert fish waste into usable nutrients for the plants. The biofilter can be its own separate component in the system, or you can cultivate a biofilm of bacteria inside the actual fish tanks and hydroponic reservoirs. Without a colony of bacteria, your plants will be unable to use the nutrients in the water from the fish (and fish will die from too-high levels of ammonia)!

The Secret to Success with Marijuana & Aquaponics is Patience

The secret to any successful aquaponics system is patience! You need to create a balance between the fish, bacteria and plants, and this takes time. Unfortunately, there’s not necessarily a lot of ways to speed things up while your bacteria is being colonized.

It’s like growing a cannabis plant in a way, you can do things to get the plant to grow faster, but no matter what you’re still going to have to wait for the plant to grow until you get to harvest. You can help your bacteria grow, but they need time to build up their numbers and form a robust colony.

That means in a young/new aquaponics tank you have to spend time cultivating your bacteria, and in the meantime you may have a lot of adjusting to do to maintain a balance that will keep both plants and fish alive: adding nutrients, changing the water, testing nutrient levels, managing pH and possibly adding/removing fish.

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But as you create more of a balance, and your tank becomes more mature, you will have a lot less to do. In fact, over time you can set the system to do most of the maintenance by itself!

3 Major Obstacles to Growing Cannabis in Aquaponics

1.) Cannabis Has High Nutrient Needs

Growing cannabis in aquaponics is similar to hydroponics, except fish and bacteria make the food! Your plants can’t use nutrients directly from the fish. Fish waste actually has to be converted to a usable form by the bacteria in your biofilter. Building a robust colony of bacteria for your biofilter can take 6 months or more, which means that additional nutrient supplementation by natural sources will likely be needed to grow a cannabis plant in aquaponics for the first few months.

The appetite of a cannabis plant for nutrients is especially voracious during the budding/flowering stage. When your plant is making buds, it’s sucking up nutrients like there’s no tomorrow! Fruiting plants with similarly high nutrient needs to cannabis (like tomatoes) have been successfully grown in aquaponics, but it’s much less common than growing something with simple and low nutrient needs like lettuce or herbs.

While “getting your feet wet” with aquaponics, don’t beat yourself up if you run into nutrient problems!

2.) May Need Separate Vegetative & Flowering Chambers

Vegetative and flowering cannabis have different nutrient needs for the best growth. So in order to completely optimize an aquaponic system for cannabis it may be necessary to maintain different tanks.

It may be possible to simply supplement your tank with extra nutrients during the flowering stage, but it can be harmful to fish to add an excessive amount of extra nutrients unless the plants use most of it up before the water is re-circulated back to the rearing tank! Extra planning and water testing may be needed to manage which nutrients are currently available.

3.) What to Do with Extra Fish

Aquaponics is spectacular at producing fish and plants at the same time. If a cannabis grower would like a constant supply of fish to eat or sell, an aquaponic system simply can’t be beat!

But if a cannabis grower does not want to actually harvest their fish, they need to plan on what to do with the extra fish as they die and need to be replaced. In order to maintain the equilibrium of your aquaponics system, it’s a good idea to regularly be adding new young fish as old ones mature and die.

Tactics for Growing Marijuana with Aquaponics

How to Produce the Nutrients Needed by Cannabis

Even after your biofilter is established, you may still need to supplement with extra calcium, iron, potassium and possibly phosphorus to keep up with the needs of your cannabis, especially during the flowering stage.

Luckily there are natural sources to get extra nutrient supplementation without seriously affecting your fish. For example Maxicrop is a common nutrient additive made out of seaweed that works well in an aquaponics system to add potassium and trace minerals without hurting your fish.

Other common additives include cycling calcium hydroxide (hydrated lime or builder’s lime) and potassium carbonate (bicarbonate), which add calcium and potassium to the system while also raising the pH (since low pH is common in an aquaponics system that’s not well-established).

No matter what, when dialing in your aquaponic system it’s important to test your water throughout the process to see what nutrients are currently available. This lets you know where you’re running into nutrient problems, and also will help you know what to do to fix it. Not only will this help you take better care of your plants, it will also help you take better care of your fish!

Want to create a complete ecosystem with basically no input from you?

Some growers will introduce a worm farm (vermicompost) to the system to supplement nutrients naturally while breaking down the solid waste from fish which can’t be processed by bacteria. This is one way to actually “complete” the cycle inside the system.

Normally in aquaponics, these extra solids are filtered out and thrown away, but worms can liquefy it while providing an extra source of nutrients that can help bridge the nutrient gap and make sure cannabis is getting everything it needs without any extra supplementation.

At this point your main input into the system would just be fish feed. If you want to get even more sustainable, you could grow duckweed or another plant that fish eat and you wouldn’t even have to buy fish feed anymore! As the system gets more and more balanced, nearly all the energy input to the system can come from the sun or grow lights, producing a food/plant generating machine!

Ready to start growing cannabis with aquaponics? The following incredibly high-rated book will teach you everything you need to know so you can get started today!

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Learn how to grow cannabis with aquaponics with Aquaponics Gardening: A Step-By-Step Guide to Raising Vegetables and Fish Together available on Amazon!

By following the tutorials and setting up your system to grow high-nutrient, flowering plants plants like tomatoes or corn, you will be giving your cannabis plants everything they need to succeed!

Aquaponics, what is it and can it work for weed?

Aquaponics is similar to hydroponics in the way that marijuana grown in an aquaponics system are grown in water. However, with hydroponics you really only have two components – the water, which carries the nutrients, and the plants. When aquaponics are used for growing cannabis, you’re actually creating an entire ecosystem, one in which many different components – fish, plants, waste, and nutrients – all work together to better the health of the entire system, and everything within it.

How does aquaponics work?

Aquaponics works very similarly to hydroponics. The plants sit just above the water with their roots dangling into the water so that they can absorb the nutrients that pass through the water. With aquaponics however, that water below also contains fish, and it’s all contained in an aquarium or other appropriate container.

Aquaponics all starts with the fish. You feed the fish, and they turn that food into waste, which is actually microbes and worms that serve as the perfect nutrients for the cannabis plants. The plants will also absorb microbe nutrients from any uneaten food that is missed by the fish and left in the tank. The plants also filter the water, providing cleaner and healthier water for the fish to live in. Aquaponics is a basic system, but one in which every component is dependent on the other to ensure success.

This setup is not only unique; it’s also much cheaper and lower-maintenance than using a hydroponics system alone. When you first build an aquaponics system, it is likely that you’ll need to add extra nutrients for your plant’s health. However, after a little time, the bacteria and microbes of the system will have built up enough that the entire system should pretty much run itself. Of course, plants will still need maintenance other than simply being given nutrients and the fish will need to be fed regularly. However, you won’t need to invest nearly as much time in an aquaponics system as you would a hydroponic system, or a standard indoor/outdoor grow site.

Aquaponics systems are good for either small or large operations, but you’ll find that even small operations might turn out to be larger than you thought. With aquaponics, plants can be kept much closer together than they typically can, so even small scale systems can provide a plentiful yield.

The Pros and Cons of Growing Cannabis Using Aquaponics

Seasoned cannabis cultivators looking for large yields and a quick growth cycle might want to consider aquaponics. Chris Bond examines the good and bad when it comes to growing marijuana in an aquaponic setup.

How to grow cannabis hydroponically is well documented at this point. There are hundreds (if not more) of resources, articles, and how-to manuals on growing marijuana with a hydro system; not so for aquaponics. The difference between a hydroponic system and an aquaponic system may seem like only a matter of degree, but there are some definitive differences to consider.

Aquaponics is the marriage of two distinct farming or production systems combining fish farming with plant production. When it works, the results can be amazing; if it doesn’t go well, you lose two potential crops, not just one. It is not something necessarily advised for the novice cannabis grower, but may provide a fun and unique challenge to one who has already mastered some of the finer points of hydroponic cannabis production.

The Basics of Aquaponics

In almost all aquaponics systems, water circulates between the section where plants are being grown and a separate section where fish are being raised. There are numerous configurations to achieve this. Some setups have the plants directly above the fish, and some have the two systems separated in different rooms but are attached by an intake pipe and a return pipe, ensuring that the water continuously cycles between the plant roots and the fish tank.

Any plant that can be grown hydroponically should be able to be grown aquaponically (I say “should” as I cannot find any verification that all such plants have indeed been tested in an aquaponic system). The choice of fish breed, however, is somewhat limited to those that can be raised in such tight quarters in water appropriate for hydroponic plant production. Overwhelmingly, the fish species selected are one of three: tilapia, perch, or trout. Those with larger tanks can try catfish and those who are not interested in consuming the fish can raise goldfish in an aquaponic assembly.

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In any healthy, balanced aquaponic system cannabis plants enjoy a continual supply of nitrogen created by the fish waste. These flow from the fish tank and can be absorbed by the plant’s roots. The plants will also get some lesser micronutrients as a side benefit, but overwhelmingly they get nitrogen. The fish get clean water as it is oxygenated and purified by the plant roots. In most systems, fish food will need to be added as well. When your cannabis plants need additional nutrients, they can be applied directly to the plants without entering the recycled water supply when a “double root zone” system is employed.

This involves creating a physical barrier between the top portion of the roots and the section that is submerged in the water. Many creative solutions and media are used for this, including various types of mesh or burlap (untreated) along with soil or other media with nutrient-holding capacity. This allows for targeted applications of nutrients such as phosphorus and potassium to the root zone, while staying out of the water supply. Foliar feeding of nutrients can also be performed if the double root zone method is not utilized.

The Pros of Growing Marijuana via Aquaponics

Most successful aquaponic cannabis producers cite the main reason for using this production method (besides producing fish as well) is that their plants can often be harvested an average of about 10 days sooner than by utilizing other growing methods. If your goal is a quick turn-around, aquaponics is certainly a cannabis growing method to consider. It is also thought to contribute to higher yields when compared to other growing methods.

Other growers cite environmental concerns.

Growing any crop with aquaponics saves water. Less water is used compared to those plants needing constant irrigation. Less water is also used because it is serving “double-duty” by keeping two separate crops alive and sated. Other growers like that it is a way to grow cannabis organically as the main fertilizer for their plants comes directly from fish. At the time of this writing, there are no recognized certifiers for organic aquaculture of cannabis; it can still be grown without using any artificial chemicals. This also results in organically raised fish for your table or to sell as an added bonus.

Regardless of the reasons for choosing aquaponics for your cannabis production, there are some very real considerations to make before jumping in.

Aquaponic systems are neither cheap nor easy to operate. They may be comparable in cost and only slightly more complicated than most hydroponic systems, but nonetheless they still cost more to set up than most soil-grown cannabis operations. It is likely additional filters will need to be set up, plus bigger pumps and larger tanks than are needed to grow a comparable amount of cannabis using only hydroponics. They are also significantly more complicated.

A successful aquaponic cannabis grower must be in tune not only to the needs of one crop and growing system, but essentially two. The grower must understand not only the needs of cannabis plants need at any given time, but must be aware of the state of the environment the fish are living in as well. It is even more vital than with a hydroponic system that the pH, temperature and electrical conductivity levels are constantly monitored. If one is out of balance, the whole system can collapse faster than more simple growing systems. This typically requires more time spent tending to an aquaponic system than any other growing method. To further complicate matters, the time required to go from seed to harvest is considerably less than it takes to go from a fingerling (the term used for many young fish) to the frying pan.

Expect the fish to take several months longer, meaning that you may be halfway through the cycle of a second crop of cannabis when you need to harvest the fish and add new ones to the system, all while trying to maintain proper levels.

Producing cannabis aquaponically is not a method generally recommended for those just dabbling in production or those who are just starting out as hobbyists. It is a step best undertaken by those who have graduated from successfully growing in soil or soilless mediums, and are ready to challenge themselves. Mastering hydroponic cannabis production, while not a prerequisite, will give the aquaponic cannabis grower a leg-up when attempting to set up and operate a viable and high-yielding aquaponics system. Once you have mastered this level of dominion over both flora and fauna, you can take pride knowing that you have reached one of the higher echelons of cannabis production.

If nothing else, fish can be a whole lot more interesting to watch while they are swimming around as you enjoy some of your aquaponically-grown bud.