What are the Disadvantages of Aquaponics?

Hydroponic lettuce varieties growing in a commercial greenhouse.

There are a few negative points that you’ll need to weigh up if you are thinking of growing fish and plants aquaponically. (There are, of course, lots of positives to farming aquaponically. For more on the advantages, read our article.) So here are some of the main disadvantages of aquaponics.

Aquaponics is Not Suitable for All Crops

Aquaponics may be great for some plants such as lettuce varieties and tomatoes, but it’s not the solution for all.

Hydroponic lettuce varieties growing in a commercial greenhouse.

Not Good for Root Vegetables or Tubers

Whilst aquaponics can be a game changer if you want to grow lettuce leaves, you’ll be disappointed if you are a would-be potato farmer. This is because tubers and root vegetables such as potatoes, carrots, yams, parsnips and so on prefer to grow in soil and with aquaponics the soil is replaced by water.

It’s not impossible to raise tubers aquapnoically and there are reports of growers raising successful potato crops using the method, but it is challenging and you will have to decide if the results are worth the effort.

Not Good for Grains

The scale of the infrastructure needed to produce the equivalent to a field of corn using an aquaponic set up is mind-boggling.

As with root veggies and tubers, just because it might be possible to grow wheat this way does not necessarily mean that you should. The fact of the matter is that it is sometimes cheaper (both financially and environmentally) and easier to grow certain plants in soil, the old-fashioned way.

Cost of Electricity

Aquaponics relies on input from 2 life forms – the filtering plants and the waste/nutrient supplying marine creatures. Anyone who has owned an aquarium will tell you that fish and other marine creatures can be very sensitive to temperature change and need looking after.

This means that you may have to invest in water pumps along with coolers and/or heaters to keep the water temperature constant and your scaly friends healthy and happy. Running pumps, heaters and so on 24 hours a day can take a lot of electricity if you are running a large aquaponics system. This can really push up the running costs of your set up as well as being bad for the environment.

If you’d like some further insights into this drawback, you can read more here.

Set Up Costs

One of the big disadvantages of aquaponics can be simply getting started.

The cost of getting your first aquaponics system up and running can be quite dear.  You need tanks, fish, fish food, plants, growing media, net pots to hold the plants and either netting to keep bugs etc off or, if you want to go the whole hog, a greenhouse. And you probably need water pumps, heaters and coolers to keep your fish etc happy depending on the climate where you live.

If you want to start off small and comparatively cheaply, It’s possible to rig up a simple aquaponics system at home using an adaptation of the Kratky method. 

Usually the Kratky method is a passive hydroponic technique where plants are positioned above a tank of nutrient-rich water with their roots dangling into the liquid. It’s pretty easy to add fish to the tank of water and run your Kratky apparatus as an aquaponic system.

However, whether you use the Kratky method or go for a complex structure, there are a number of problems that you may come across, the main one being water temperature. As I mentioned above, fish like constant water temperature, so you may need to invest in water heaters or coolers and pumps if you don’t want to replace your fish every few weeks!. Purchasing items like this can quickly push up costs, especially if you plan to run a number of larger tanks.

Expensive to Upscale

Setting up an aquaponics system may seem expensive in the first place, but expanding the apparatus for large scale production hits a whole new level of cost.

If you want to move beyond a few fish tanks and plant trays in your greenhouse at home and have plans to use aquaponics for commercial farming, you will need a lot of space, a lot of equipment and will use a lot of power. 

Large aquaponic farms also need a large workforce to tend to the fish and plants – checking water quality and temperature, feeding the marine life and so on.

Disadvantages of aquaponics demonstrated by the scale and cost of a commercial set up growing lettuces

Needs Technical Knowledge

If you grab a handful of goldfish from your local pet shop, bung them in a tank and dangle the roots of a few lettuce seedlings into it, the chances are that either your goldfish or your lettuces – or both – will die. 

Both marine creatures and plants like particular conditions for them to thrive. Different fish and molluscs like varying water temperatures and they don’t like that temperature to vary too much. Similarly, different plants prefer specific nutrients in their water supply and so the life forms in your water tank need to be compatible with your plants. 

Most importantly, you need to have the right type of bacteria in your set up to break down the ammonia-based waste produced by the residents of your tanks and turn it into delicious nitrogen-rich food for your plants. 

Overall, this means that there is quite a lot of water temperature and quality and nutrient-monitoring needed to optimise an aquaponics system and you need to know what you are aiming for before you begin buying state-of-the-art kit, plants and fish.

Not A Lot of Fish

It may seem like a bit of a quibble, but unless you are running a very large aquaponics structure you won’t be eating fish for dinner every night.

Admittedly, getting 2 crops from one cultivation system is one crop more than most systems produce and any fish or molluscs can be seen as a bonus, but fish need space to thrive and most home aquaponics structures can’t accommodate more than a few creatures. Plus over-stocking small tanks is cruel.

One Part Fails, It All Fails

As aquaponics acts as a closed loop – with the fish providing nutrients for the plants and the plants filtering the water for the fish – if one part of that loop fails, the entire system will go down.

If your trout die there won’t be any waste to fertilise your tomatoes and you will lose 2 crops rather than the usual one.

Overall

Aquaponics offers a lot of benefits to the adventurous home gardener and can be incredibly rewarding, but it needs sufficient research and understanding before you launch into buying expensive equipment and wiring up power supplies. 

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