Complete Guide To Growing Cannabis With Aquaponics

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Added 28 December 2021

Do you want to take your cannabis cultivation to the next level? Perhaps you want to make it more automated, organic, or simply build a system that looks cooler than anything you've ever tried?

Well, say hello to aquaponics.

Many growers stay away from organic farming because the yields are not as good as hydroponic techniques. However, aquaponics allows you to grow organic cannabis with excellent results that match hydroponics. In short, you can now grow organic weed using very few resources.

How? This article will explain how you can grow cannabis using aquaponics. Here’s a quick guide to producing the best possible organic cannabis.

What is Aquaponics?


Although aquaponics sounds like a new concept, it is perhaps one of the oldest. Aztec Indians practiced aquaponics way back in 1150 AD. They created small artificial islands on lakes using reeds and grass. 

These islands or "beds" would hold the plants with their roots suspended in the water. Then, rather than feeding fertilizers to the plants, they let the lake's natural ecosystem feed the plants. In other words, the plants used fish waste to grow, and the Aztecs grew various types of vegetables. Since then, aquaponics has spread to many other countries and is quite a hit in areas with water bodies.

Today, you can set up a similar system at home and grow cannabis. If you've ever shied away from organic farming because of its reputation to produce fewer yields compared to hydroponics, aquaponics is your savior. 

Generally speaking, growing organic cannabis is excellent, but hydroponics is always better. Why? Because hydroponic cannabis allows you to feed the plants precisely what they need. You can calculate the exact amount of nutrients, and everyone's happy. 

Of course, you will need to dial in the pH and do everything to the T to ensure the system works fine. Organic cannabis growing projects, on the other hand, don't need precision. You can grow plants with just manure and get good results, but the yields are different from hydroponic systems.

Aquaponics systems bridge the gap between organic cannabis and hydroponics. Not only does it allow you to grow organically and enjoy the taste of cannabis without any added chemical fertilizers, but you also get excellent yields, very much like hydroponic systems. Yes, you will have to monitor the pH even in aquaponic systems, but we will tell you how to do that in subsequent sections. 

In summary, aquaponics is a unique way to grow plants. It combines fish farming and hydroponics to gain excellent results. Although it is a little complicated to set up, aquaponics is a breakthrough technique that has revolutionized organic cannabis farming.

Essentially, to grow cannabis with aquaponics, you have to create a cannabis biodome, which is self-sustaining. This biodome acts as an alternative to a growing operation where the system maintains a symbiotic relationship between your cannabis plants and pet fish. 

The fish waste feeds the plant, and the root zone acts as a biological filter to clean the water. You can set up this system both outdoors and indoors.

Benefits of Growing Cannabis with Aquaponics

Advantages of aquaponics

Many growers use aquaponic systems because they offer a variety of benefits. Let’s take a look at them in more detail.

Flavourful buds

Since this system is entirely organic, the buds are delicious, smooth, and potent. You can even get 10x the yield compared to a regular cannabis plant!

Completely organic and natural

The aquaponics cannabis system is entirely natural as it does not require any chemicals or fertilizers. Plus, it keeps your fish healthy and happy! In addition, it is possible to produce both cannabis and fish using one system. 

Uses less water

Aquaponics can save up to 90% water as it is entirely self-sufficient, and the water is filtered and reused constantly. As a result, you only have to top-up water lost due to evaporation.

Easy to set up

Once you get the basics clear, you can set up your aquaponics systems virtually anywhere — outdoors, greenhouse, bedroom, basement — wherever you want.


Aquaponics also requires a lot less effort and time than other cannabis cultivation methods. Just remember to feed your fish on time, though!

Bragging rights

Many people have indoor plants or grow their own cannabis, but how many people you know have an automated, self-sustaining system with an aquarium underneath? That’s right. Aquaponics is a quirky, fantastic way to grow cannabis.

Barriers of Growing Aquaponics Cannabis

Disadvantages of aquaponics

Complicated for beginners

Despite its benefits, aquaponics isn’t for everyone. If you are a new cannabis grower, we don’t recommend you choose aquaponics to grow cannabis as you need to know the basics of both hydroponics and fish farming.

You also need to figure out the optimal fish to plants ratio, which is not easy to do. So you will need to experiment a bit. 

Lastly, if you plan to grow aquaponics cannabis for the longer haul, you need multiple systems to rotate your crop. For instance, one system will have to be dedicated to vegetative plants and the other for the flowering plants, with their respective light cycle conditions. However, since you will need to plan this approach regardless of the system you use, it’s not limited only to aquaponics. 


You already know that it’s an expensive hobby if you’ve tried fish farming. And, combining hydroponics with that? Then, of course, it gets costlier. A small aquarium could cost hundreds of dollars. Plus, you can’t skimp on the quality because you want something reliable, sturdy, and lasts a long time. Imagine investing in a cheap system only for it to break down suddenly and kill your plants. 

In addition, fish need warmer waters, so you may need to invest in additional equipment if you reside in colder regions. Conversely, those living in warm areas may need cooler water for the fish. Generally, the fish will do well in temperatures ranging from 20-30 °C or 68-86 °F. 

In simple terms, aquaponics could get quite expensive. But, the good news is that once you cough up the initial costs, you get to gain a lot more in the long run, especially if you’re a commercial producer. 

How to Set Up Cannabis Aquaponics

You’re halfway there if you already have an aquarium or a hydroponics system. But we’ll still start from the basics so you can get a complete understanding of the aquaponics system. So here’s how you can get started quickly.

  • Set Up Your Fish Tank

Set up the tank

First things first — fish are living beings, and you want to give them a safe and comfortable environment to live in. So, let’s start with setting up their home.

Get a standard acrylic aquarium and add some water to it. Remember, the water must be dechlorinated. An easy way to dechlorinate water is to let it sit for a couple of days to allow the chlorine to dissipate.

Next, you’ll need some fish, but don’t add them to the tank just yet — you need to cycle the system for at least a month before that so the bacteria can grow in the water. Cycling is nothing but establishing a large colony of organisms or bacteria that helps with the nitrogen circulation in the system. Failing to do this will result in a failed system as it won’t have the necessary bacteria to provide the plants with some nutrition. 

The process begins as soon as you add some pure ammonia to the water. The ammonia naturally attracts bacteria from the atmosphere but you can also add some from external sources for faster results. You can either purchase bacteria meant for aquariums from local pet stores or do it online. 

To ensure that the system is cycled, you will need to test nitrogen levels, including ammonia. For this, you’ll some high-grade pure ammonia that you can purchase from local stores, or you could get kits online that include ammonia, bacteria, and seaweed as well.  

At first, the ammonia will increase, but it will come down as the bacteria consume it and turn nitrite into nitrate. Do not use too much ammonia as it will kill all the bacteria! You'll need to test the levels of ammonia every day if you've already added fish. If you haven't, though, it's not a big deal. You also need to install a pump to circulate water from the fish tank into the grow bed and vice versa. 

  • Add the Fish

Add the fish

Now, it’s finally time to add the fish, but do it only when the system is cycled properly. This process could take at least a month or so, but once it’s done, you can start adding some fish to the aquarium. We recommend choosing fish such as goldfish, koi, barramundi, tilapia, ornamental fish like guppies or mollies, catfish, and trout. 

If you choose to add various fish species, ensure they are compatible. You don’t want your cannabis growing system to be a battlefield for fish!

  • Build the Media Bed

Media bed

You need to build a dual root zone media bed to hold the cannabis plant. But, first, you’ll need something to hold the plants. Like hydroponics, net pots will work well. Some growers may use the tray itself without the pots, but it could be slightly tricky to manage. 

Next, you’ll need something to hold everything, including the net pots, so start by installing a media bed in a flood table setup right atop the fish tank. We recommend using heavy-duty plastic trays. Once it’s set, ensure it is sturdy.

Then, add a layer of clay pebbles to the tray or net pot. The pebbles or hydroton make an excellent growing medium as they are pH-neutral and free of any nutrients so that they won’t affect the water within the system.

Since it is a dual root zone, we will add another layer of permeable material like burlap over the clay pebbles. Finally, add a layer of pH-balanced soil on top of the burlap. Therefore, the growing tray or net pots will contain pebbles, burlap, and some soil on top in layers. 

Doing so will make a dual root zone — one aquatic and one terrestrial. This zone will help form a self-sustaining ecosystem that can harbor beneficial bacteria to help the plant grow properly.

You're now probably wondering about a dual root zone and how they help aquaponic systems. Essentially, dual root zones separate the soil from the remaining material. Remember the burlap you used? It separates the soil from the hydroton and other material without suffocating the roots.

A dual root zone works like a charm because you can now have your microbes in the soil at the top and amend it as you like without disturbing the marine layer below. This system also allows you to retain nutrients for extended periods while allowing gas exchange to provide nutrition to your plants.

Also, the fish do their best to provide nutrients to the plants, but cannabis plants often need more nutrition. There is no shortage of nitrogen, but although the fish waste provides a lot of nutrients, the water may lack some phosphate and potassium that are critically important for the plants during the flowering stage. Therefore, if you rely solely on the nutrients from the fish, you will see the plant struggle with some nutritional deficiencies in the long run.

Therefore, a double root zone helps you amend the soil with nutrients and prevent nutritional deficiencies without disturbing the aquatic layer below the setup. 

Once you gain enough experience to understand how much water the top layer of soil holds, you can treat it like a regular plant growing in soil and water it separately. Essentially, you can add fertilizers rich in potassium, phosphate, or any other nutrient without worrying about contaminating the fish water. 

So why is a double root zone important? Basically, it allows you to add phosphate and other nutrients that may be harmful for the fish but are necessary for cannabis without disturbing the intricate ecosystem.

  • Transfer your plants

Transfer the pots

Once the system is ready, you’re all set to start growing your cannabis plant. First, germinate the seeds if you haven’t done so already and wait a while until they develop at least two nodes. However, if your plants are ready, transfer the plants with the net pots to the system. 

Once you get familiar with the aquaponics system, you will dial in the fish to plant ratio as the system is more or less automated. The closed-loop system will do most of the work for you. 

Just ensure your fish are healthy and well-fed, and the system will take care of your plant.

But, wait…what about the pH? Is it even necessary to control the pH for aquaponics systems?


Importance of pH in aquaponics systems

Growers who use hydroponic systems to grow cannabis always watch the pH. On the other hand, those using organic methods to grow cannabis don't need to obsess over the pH because you are essentially feeding the bacteria in the soil rather than the plant.

Aquaponics is an organic method to grow cannabis — you already know that — but unlike other organic techniques where you don't need to worry about the pH, managing the pH is critical to work with an aquaponics system. In fact, maintaining the pH is the trickiest for aquaponics systems because you have to consider three primary elements including fish plants and bacteria.

All three elements prefer a different range of pH. For example, while the plants prefer slightly acidic pH levels (5.5-6.5), the bacteria and the fish love slightly alkaline levels of pH (7-8)! This means that you will have to balance the three elements to ensure you get good results in the end. 

Suffice it to say that a range between 6.8-7 will work as a sweet spot. Agreed, the range is too tight, but this is an ideal range if you want to create a balance between your plants and the other living organisms in your aquarium.

Without the fish, the plants will not get nutrients, and without the bacteria, there's no way for the plants to use the nutrients. So both the fish and the plants will die without the beneficial bacteria.

The waste the fish generate will automatically make the water acidic, but it's not a good environment for the fish, so it's critical to keep an eye on the pH levels at all times. Simply put, the system can crash or stop working suddenly if you don't maintain the pH.

All this talk about the pH must have gotten you really worried by now. You were just about dreaming about an aquaponics system, but the pH is now making you second guess your decision, right? Well, don't worry — although it is essential to maintain the pH in aquaponics systems, it is easy to do so.

Remember the process of cycling the system we discussed earlier? Well, the good news is that you've already begun the process of adjusting the pH as soon as you start cycling the system. Next, you add nitrifying bacteria that take over the system and process the fish waste so the plants can use the nutrients. Since this cycling process is geared towards the fish and the bacteria, you can also use tap water in aquaponic systems.

No matter where you live, tap water generally contains pH levels above 7 because municipalities use slightly alkaline water to prevent the corrosive effects associated with acidic water. Since both the fish and the bacteria prefer water with a pH above 7, tap water is actually beneficial to cycle the system and kick-start the process.

We already discussed how ammonia is converted to nitrates, so we won't get into a science lecture here. However, just know that once the nitrogen cycle establishes itself, the pH decreases gradually. In fact, as you gain more experience growing plants with aquaponics over time, you'll see the pH fluctuating randomly due to many other processes occurring simultaneously. So, as the nitrogen cycle creates nitric acid, it automatically reduces the pH levels. At times you may even need to reduce the pH levels deliberately. Conversely, you may even have to increase the levels. Basically, you'll have to monitor pH closely.

How to Adjust the pH for Aquaponics Systems

Now that you know the importance of pH, let's figure out how to adjust it for aquaponics systems.

In hydroponic systems, you generally use acids or bases (pH UP and pH DOWN) to lower or raise the pH levels of the water. Similarly, you can use acids such as muriatic, phosphoric, and nitric acid to reduce pH levels in aquaponics systems. However, do not use citric acid, an antibacterial agent, as it can kill the bacteria.

Most growers use phosphoric acid because it is considered the safest and is also an ingredient in soft drinks. In addition, phosphoric acid, as the name implies, adds phosphates to your aquaponic system. Although the plants love phosphates, they can increase algae, so don't use more than necessary. Also, the bacteria and the fish do not appreciate extra phosphates in the system.

Conversely, to increase the pH levels, you can use potassium or calcium carbonate individually or add small and equal amounts of both simultaneously. Some growers may also use potassium hydroxide or calcium hydroxide for the same reason; however, both the hydroxides can be as dangerous as acids and burn you if you handle them without gloves. They are known to be caustic for a reason.

Although you have a tight pH range in aquaponics systems, it becomes a no-brainer over time as the entire system is automated. As long as you ensure no drastic changes in pH levels, you will be fine. This means that you create a buffer, so the pH alters slowly without disrupting the bacteria or the fish.

Why is it important to create buffers in aquaponics systems?

As mentioned already, you will need to consider the fish, bacteria, and plants when adjusting the pH levels in aquaponics systems. The fish also adjust to your desired pH levels over time, but they do not survive sudden changes. Therefore it is vital to create a buffer.

Typically, water hardness comes in two types — KH or carbonate hardness and GH or general hardness. KH also refers to the water's capacity to buffer, while GH usually refers to the amount of magnesium and calcium ions in your water. Therefore, KH is the critical factor that buffers whatever your water soaks up in its system.

So, to maintain the pH levels, you can start by measuring the KH levels for better results. Higher KH levels mean that your system is resistant to alternations, which is why there are no or slight changes in the pH levels even if you add lots of acids. It's best to maintain KH levels less than 4 dKH to prevent rapid pH swings. 

In addition, if you see that the fish suddenly starts dying, it's time to measure the pH levels, and if you notice that it's swinging rapidly, you will have to test the KH levels. Also, failing to maintain appropriate KH levels would mean constant pH monitoring daily, which is simply not easy.

Summary: Your Guide to Growing Cannabis with Aquaponics

Growing cannabis with aquaponics is a terrific way to improve your yields TOTALLY ORGANICALLY. You will still require some trial and error initially, but don’t give up. Once you figure out the nuances of growing aquaponics cannabis, you can enjoy the best homegrown buds!



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Great article! Sure would like to see some examples on what to do right and wrong. Might be a perfect Spring project. Five thumbs way up!