Saltwater Aquaponics?

Saltwater Aquaponics?

Is it possible to set up a saltwater aquaponics system to grow vegetables? I’ve never seen or heard of such an installation but the topic is occasionally raised among those new to aquaponics. An honest query really considering saltwater shrimp, shellfish and/or fish such as red drum are valuable and sought-after livestock.

Taking this a step further, saltwater aquaponic installations would look a lot cooler when you have damsels, tangs, butterfly, rays and sharks swimming around vs freshwater species which look rather dull in comparison.

Aquaponics can only use freshwater, right?

I’m guessing most aquaponic farmers believe as I, salt water would kill most vegetables. Given this accepted tenet, we’d therefore use only fresh water and freshwater fish such as tilapia, bluegill, trout, perch or catfish. However, let’s consider the potential of using saltwater given more than 70 percent of the world is covered in it! This would definitely boost overall food production on the coasts where most of the population lives.

Vegetables tolerant of saltwater

To my surprise, there are plenty of vegetables tolerant of salt water. Following is a post about salt-resistant crops: Here is another article exploring the same:

Saltwater Crops

This article is about a Dutch farmer looking to grow potatoes using saltwater:

Saltwater aquaponics for purely saltwater crops

So let’s take this even a step further. Rather than building and experimenting with growing traditional vegetable crops in saltwater, why not grow saltwater aquatic plants with commercial value in these systems. Seaweed is a great example and here’s an article about growing this crop using aquaponic methods:

More on saltwater aquaponics at this wikipedia page:

Patio Aquaponics System First Planting

Patio Aquaponics System First Planting

Now that our patio aquaponics system is well into cycling after the introduction of tilapia, we are ready to plant our first seeds in the grow bed. As you may recall, cycling is the process of building beneficial bacteria in the system in order to efficiently convert fish waste into nitrates and nitrites, which our plants will eventually use as fertilizer. It’s time to add those plants — if not, nitrate levels could reach a toxic level which could kill the fish.

Heirloom organic seeds

We’re exclusively using heirloom organic seeds so we purchased our first batch of romaine lettuce from Annie’s Heirloom Seeds. Annie’s ships their seeds in standard USPS and are packaged in branded packets. We were a little disappointed in the number of seeds for the money you pay ($2-3 per packet, with $7 shipping charge) so we’ll explore other sources to see if there is a better value for farming on a small scale.

We understand these seeds are better quality than what you’d purchase at the local big box store, but I think you still need to match volume since those seeds are only $1-2. Plus, we’re starting to see a lot of branded seeds options on the market (think Martha Stewart), that are not heirloom, nor GMO-free but get into the $2-3 price point as well — and those packets are loaded.

Use of rock wool

Some aquaponic farmers throw seed right into the hydroton pebbles but we prefer to set them in rock wool, then place these cubes in hydroton. Although we’d space these wider in a large outdoor system, we’re unsure of how much we could squeeze in our system. For this planting, we’ll space them about three inches apart.

As they grow under artificial light, we could easily lift the rock wool out of the hydroton to re-space. This is the primary reason why I choose to set in rock wool first. We’ll do our best to space as tightly as possible without sacrificing plant quality by stunting growth.

Seed germination

Seeds germinated after two-three days and are growing vigorously. Although we have not hit the recommended 30 days for a tank to completely cycle, we suspect there is enough fertilizer in the system judging from the vigorous growth of the seedlings. I’d consider our first planting in the patio aquaponic system a success.

We plan on planting arugula, bok choy, escarole, water cress, mustard and basil in the future.


Small-Scale Aquaponics Patio System Build

Small-Scale Aquaponics Patio System Build

Having no yard to grow our own vegetables living in an apartment, it was tough to accept having to buy vegetables at the market. Therefore, we committed to building a small-scale aquaponics installation around a 55-gallon tank destined for our patio. Small-scale aquaponics systems you can buy online will not satisfy our needs. They are either too small to grow a substantial amount of food or pragmatic DIY constructions lacking aesthetics. We didn’t want to add that motley collection. We wanted it to be presentable as well as durable.

Good Aesthetics Starts with Wood Selection

With these considerations, we opted to use select pine appearance boards which are smooth to the touch and are easy to work. The pine serves as both the framework around the tank and material for the grow bed. To match other outdoor furniture, we stained all the pine with blue Minwax water based wood stain and coated it with Minwax polycrylic finish. Construction of the tank framework and grow bed only took about six hours. What took lots of time was applying the stain and finish. This process lasted a week to apply several coats of stain, finish and waited for each application to dry.

Small-Scale Aquaponics System Construction

Rather than use water proof paint in the grow bed, we used 6 mil vizqueen as liner. The liner could easily be replaced when necessary without having to worry about water leaks or seepage into the wood. We drilled a hole in the middle of the grow bed to install a bell siphon, a truly amazing, yet simple technology critical for flood and drain aquaponic systems.

The bell siphon is constructed using PVC reducers combining a 3 in. x 2 in. PVC reducing coupling to a 2 in. x 3/4 in. PVC Schedule 40 reducer bushing which is connected to the 3/4 PVC Schedule 40 drainage pipe that flows back into the fish tank. The “bell” part of the siphon is cut from a piece of 4 in. x 10 ft. PVC Sch. 40 plain end pipe and a 4 in. PVC sewer and drain cap. More on bell siphons in a future post.

At the heart of the aquaponic system is a pump that lifts water from fish tank to grow bed. We chose a 400 GPH submersible pump from Amazon. All of the plumbing to connect the pump to the grow bed and used as irrigation was constructed using schedule 40 PVC 3/4 pipe.

Testing Out the Small-Scale Aquaponics System

So how does all this work? As water is pumped into the grow bed, it raises the water level to the point where it begins to trickle down the drain pipe within the bell siphon. As the trickle builds down the pipe, a vacuum is formed within the bell siphon which triggers a full powerful drain which empties the grow bed faster than the pump can fill it with water.

The siphon vacuum is broken when there is no water left to drain, air enters through the bottom of the siphon and the grow bed begins to fill again. This allows the grow bed to drain at regular intervals which is the purpose of a flood and drain system.

Lighting and Containers

Since this would be on a covered patio, we needed to install lighting over the grow bed. We used 12W LED replacements for T8 fluorescents from Home Depot since we wanted to reuse the T8 housing we already had. We also purchased 16 square plastic (5.5×5.5x6in) hydroponic pots for the grow bed from Hydrofarm. More updates soon!

Why Use Aquaponics on an Apartment Patio?

Why Use Aquaponics on an Apartment Patio?

Pepper and Eggplant

Eggplant and peppers showed extremely anemic growth.

Growing vegetables on a patio in dirt-filled pots seems like an easy endeavor, but theory does not always translate to practice. Why use aquaponics as an alternative? Let us explain.

Aquaponics vs Pots for Growing Vegetables

Following are challenges with growing in dirt pots: 1. you needed to carry dirt which is heavy — especially tough when you’re on the fourth floor; 2. the soil is devoid of nutrient content or it was mystery to the amount of nutrient content it contained; and 3. you don’t necessarily get enough sunlight for the plants to grow healthy since patios are usually covered. Sunlight, if you are lucky, comes in at angles, either in the morning or late afternoon. We discovered why so many patio gardeners try and fail — and probably never try it again.

Aquaponics using LED Lighting is the Solution

However, we didn’t give up and turned to what worked for us before, aquaponics using artificial lighting. Yes, water is heavy too but it can be poured with a hose and drained! And in regards to the nutrients, aquaponics is a mutually beneficial system where fish waste supplies nutrients (nitrogen) for plants, which in turn would remove these elements that would be toxic to the fish. More on the benefits of aquaponics here.

LED lighting is the ideal solution for dimly lit patios (or deck surrounded by lots of trees). Although expensive to purchase, they are low power consumers, could potential provide the right, if not perfect wavelength of light and be turned on and off using a timer so you have complete control of the growth using this lighting.

Growing Vegetables Using Two Organic Practices

During the last six years in Virginia, we grew our vegetables in 8 raised beds, filled with rich compost sourced from foliage, yard waste and surplus vegetables; and in two custom-built aquaponic systems. Read about benefits of using aquaponics here.

Our primary aquaponic system was a large installation outside which grew mostly stem plants such as peppers, tomatoes and basil using bluegill as the livestock living in a 600 gallon pond. We also had an indoor system which we grew mostly leafy vegetables such as bok choy, lettuce and arugula using tilapia as livestock in a 70 gallon tank.

Pot Gardening on Patio

Vegetables grown in post yielded no real success. We used bagged dirt in pots.

Have A Fish Tank? You Have a Potential Aquaponics System

For our small patio, we needed to scale an aquaponics system even smaller. We decided to build an aquaponic system around an old 55-gallon tank we used as a saltwater aquarium. Like our larger systems in Virginia, we will build a flood and drain system, just on a smaller scale.

As we do our build, we’ll provide updates on progress on this page.


  1. Small-Scale Aquaponics Patio System Build