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Aquaponics & Cannabis: 3 Major Obstacles

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Introduction: What is Aquaponics?

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

Fish

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.

Plants

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

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.

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!

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!

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…

Introduction to Growing Cannabis With Aquaponics

Aquaponics is a growing technique that takes two efficient systems and combines them to work symbiotically with each other: Aquaculture is the process of farming fish (such as tilapia, koi, or bluegill) or shellfish, while hydroponics is a method of growing plants without soil. When the two are combined, you can create a nearly closed loop system that produces both plants and fish for consumption.

How Do Aquaponic Systems Work?

Aquaponics setup with a double-root zone. The bottom half of the double-root zone can be filled with a hydroponic medium or the roots can be suspended in water. Click to enlarge. (Elysse Feigenblatt/Leafly)

Aquaponic setups are nearly identical to hydroponics, the main difference being the source of the nutrients for the plants. Nutrients are no longer added to a water tank–instead they are produced by waste produced by the fish. The diluted fish waste is pumped out and delivered to the roots of the plants. The roots absorb the nutrients and purify the water before it is returned to the aquarium. Fish food is the only input you’ll need, and this can be grown or purchased for the system.

The primary nutrient produced from the fish waste is nitrogen with trace amounts of other minerals. Because of this, basic aquaponic systems are effective for leafy greens, but if you’re cultivating tomatoes, cannabis, or fruit and vegetables, you’ll need to add additional nutrients like phosphorus and potassium. This is remedied by a double-root zone.

A double-root zone allows you to divide the roots into two sections. The bottom half of the pot will be submerged in the water while the upper half of the pot can be filled with soil. This allows additional nutrients to be applied to the roots without contaminating the water. The two sections can be separated by burlap, which allows the roots to travel through while preventing the soil from reaching the water. When watering with additional nutrients, avoid oversaturating the soil to keep the water in the aquaponics system clean.

Advantages of Growing with Aquaponics

Multiple Returns

If running aquaponics with consumable fish like tilapia, you’re getting a two-for-one. As your plants grow, you’ll also be raising protrient-rich fish. Generally, tilapia take between 6-9 months to reach the desired size for consumption, but speed of growth depends on the water temperature.

Sustainability

Aquaponics is a truly sustainable system for growing cannabis. Fish food manufactured specifically for aquaponics ensures your system is free of toxins, and provides the fish with what they need to grow strong and healthy. Again, all you need is fish food as well additional nutrients for your top soil layer, and you’ll be able to grow both healthy cannabis plants as well as fish for consumption.

Growth Rate

Aquaponics is a great method for fast-growing plants. By allowing the roots to take in high levels of oxygen, they are able to absorb more nutrients and grow quickly.

Water Use

Estimates show that aquaponics systems use up to 90% less water than traditional systems by recirculating water.

Disadvantages of Growing Cannabis with Aquaponics

Upfront Costs

Setting up an aquaponics system is going to be more costly than establishing a hydroponic or soil setup. If you are looking for an inexpensive way to start farming, aquaponics isn’t the system for you.

Aquarium Maintenance

Fish need water that is held between specific temperatures. If growing outside, you especially need to be mindful about heating and cooling water to keep your fish happy and the system running.

Algae Growth

As with all hydroponic systems, there’s a lot of lingering moisture with aquaponics. This requires that you be on high-alert for algae growth that can be dangerous to your plants. Systems require cleaning and sterilization to protect the plants.

Aquaponics is a sustainable and effective method for farming, but it can seem like a lot to handle when producing cannabis. No doubt, aquaponics will increase your responsibilities as a grower, but some of you might be looking for a new challenge. Witnessing the full cycle of food turned into waste and then turned into food once again for your cannabis, you’ll come to better understand many aspects of raising both plants and aquatic life.

Learn more about using aquaponics to grow cannabis sustainably, and find out whether it's the right growing method for you.