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.
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.
Read also: How to Grow Cannabis Organically
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.
Read also: Build Your Own Aquaponics System
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.