20+ Common Mistakes People Make in Aquaponics (& How to Fix Them)

Last Updated on December 17, 2018

Aquaponics may seem daunting the first time you learn about it. There’s a lot to know about aquaponics, and maybe that’s what makes it so interesting.

The idea of having to maintain the health of both a fish and plant environment can seem like a lot to take on.

common mistakes in aquaponics

Common Mistakes in Aquaponics

However, Aquaponics is relatively simple to set up and maintain. In fact so long as you be sure to avoid making these all too common mistakes you’ll be sure to avoid the headache others have experienced when starting out and be off and running in no time. So let’s dive right in!

1. Water Quality: adding poor quality or tap water into your system

Maintaining good water quality is very important. Water is the life-blood of an aquaponic system. It is the medium through which all essential nutrients are transported to the plants, and it is where the fish live.

Five key water quality parameters are important to monitor and control: dissolved oxygen (5 mg/liter), pH (6–7), temperature (18–30 °C), total nitrogen, and water alkalinity.

You have to check chlorine, pH and pathogens/parasites before you use it in your aquaponics system.

Most of the cities in the US add chlorine and fluoride to their water. Specifically, chlorine can be deadly to fish. It is advisable to test for chlorine with an inexpensive test kit.

The water chemistry may seem complicated, but the actual management is relatively simple with the help of common test kits.

If you are setting up a brand new system or have a running system and need to add water to it, you can do this by adding the water to the fish tank and letting it sit for 48-72 hours with the aeration unit going.

Check our post about water parameters that effect aquaponics

2. Not Considering Fish to Water Ratio: Adding more fish than a system can handle

Too Many fish in tank
Adding too many fish in tank stress the fish

Another common problem among those starting out is that they want to grow as many fish as possible as quickly as possible. So they end up overcrowding their fish tanks.

That doesn’t only result in stunted growth for the fish and high nitrate levels can also lead to the fish loss.

When starting out with a system for the first time, keep your stocking densities low.

Do not overcrowd the tanks. Your aquaponic system will be easier to manage and will be insulated against shocks and collapse if the stocking density is kept low. The recommended stocking density is 20 kg/1 000 liters, which will still allow for substantial plant growing area.

Remember: Higher stocking densities can produce more food in the same space but will require much more active management. 

Unless you are growing on a large commercial scale, it is highly unlikely that the fish portion of your system will be profitable. As a small scale or hobby grower, you should be looking to keep the fish side of the operation as low as possible to maximize your margins. Don’t make the mistake of over-stocking, you can always add fish later, it’s a waste to stock too densely lose fish to death or have to take them out.

Check our guide about fish to water ratio in aquaponics

3. Not choosing right Growing Media

Growing media hydroton clay pebbles
Growing media Hydroton clay pebbles

Common mistake.!

Many people start with wrong media like expanded shale or limestone, ignoring some basic factors. There are several things you have to consider before choosing growing media, check in detail here.

People prefer to use media that they can get locally and is readily available. but they don’t know what media they should use!

Check the list of all growing media here

The best Grow media is nutrient-free, neutral pH, able to retain air, able to retain water and drain quickly so that roots don’t get waterlogged. Growing media also allow the colonization for microbial populations.

Hydroton is most commonly used growing media because of its good water retention, neutral pH and easy to maintain. Check more about Hydroton clay pebbles here

4. Using harmful additives to lower the pH

Keeping pH in a specific range in aquaponics is very important. Aquaponics is a system of relationship and balance.

Some people are impatient and resort to using a chemical such as muriatic acid to lower their pH. Chemicals will lower your pH but they are untested and many of them will harm the health of your fish and plants.

If you are considering chemicals, don’t. It is that simple.

Also be careful about any quick changes in temperature or pH. Fish are it will strain the fish.

The pH of your system will drop on its own over time due to nitrification, and that gradual drop is safe for your fish.

Vinegar is a slow fix, be patient and keep the additions small.

5. Growing WRONG plantsPlants mistakes made in aquaponics: sad plant

Non-native or Non-Seasonal: If you’re going to grow non-native plants, make sure that they do well. Grow seasonal plants in their season.

Choose right fish and plants: Keep in consideration season and fish. Like, Tropical fish do well in warm water., so grow the plants that grow in summer. You’ll not bother about keeping the temperature in range for fish and plants separately.

Check this post about role of temperature in aquaponics (plants, fish, bacteria)

Plant vegetables with short grow-out periods (salad greens) between plants with longer-term crops (eggplant). Continued replanting of tender vegetables such as lettuce in between large fruiting plants provides naturally shaded conditions.

 Remember: In general, leafy green plants do extremely well in aquaponics along with some of the most popular fruiting vegetables, including tomatoes, cucumbers, and peppers. 

On a commercial level, if you’re growing plants that are low-priced in the market. You’re making a huge mistake that may cost you a lot in profitability. Tomatoes and specialty crops like yellow peppers and basil and other herbs can deliver profits that support such a greenhouse. Corn, wheat, any grain crops are examples of a crop better suited for an open field.

6. Not having a pest control strategy

If you’re keeping the system clean and in check of the different parameters, you’ll rarely experience any pest problems.

Slugs in aquaponics growbed
Courtesy: fo2oz

Since you can’t use pesticides in aquaponics, you need to be vigilant in your pest scouting efforts and quick to react if you see any pest problems.

When you spot these critters, it’s best to take care of them before they spread and grow in numbers.

There are several ways that you can get rid of them:

  • Feed Them To The Fish – They may be a problem but they are protein-rich! You can turn a problem into a benefit by setting up bug traps and catch slugs, caterpillars and other insect larvae to feed to your fishes. They will enjoy the meal and it’ll also save you a bit of money on fish food!
  • Knock Off With organic Water Spray – You can control a large infestation of bugs by spraying a stream of water at them. Also, adding an organic solution to the spray can help to repel insects as they’ll become less attracted to the plants.
  • Using Predators – Beetles, flies, spiders, and wasps are predators to bugs that harm your plants such as aphids. A common predator used for pest control is the ladybird which feeds on aphids.

You can use cultural, biological, physical and chemical methods to eradicate pests. Check more here 

7. Are your plants getting enough light?

I hear people saying that their plants are not doing well in aquaponics. And most of them are trying to grow their plants indoors or in shade.

Plants grow by photosynthesis, which requires light of at least 30,000 Lux.

If you have no access to sunlight, Use LED grow lights. If you have a small setup, these cheap and small LED grow lights will work fine.

You can also try these indoor hydroponics gardening kits that come with grow light or these small betta aquaponics tanks.

On a commercial level, use light meters to monitor if your plants are getting enough light.

8. Using transparent Fish tanks

Algae will love water and light, and they will grow everywhere they can get nutrients, in other words, everywhere the water goes by. They will grow so well that they will clog the smaller conduits, such as the tubes.

To avoid any algae problem, use opaque conduits in aquaponics, such as PVC, where the light cannot go, and without light, algae won’t grow.

If your system is placed in sunlight. Install the floats into the grow bed and cover the fish tank. Blocking out the sun kills off the algae and is removed by the filter.

9. Are your fish feeding regularly?

Most people are reckless in feeding the fish. Fish need an adequate amount of feed on the interval of time. Fish were being underfed can lead to low fertilizer nitrate levels. Use fish automatic feeder to automate this job.

10. Not checking the ammonia/nitrite/nitrate levels: High ammonia and low nitrate level?

Are your fish dying? If so, unionized ammonia or nitrite may be too high in the system, and biofiltration needs to be boosted.

Ammonia is produced by the fishes and is discharged through their gills. Ammonia is very toxic to fish and a build-up of it in the fish tank will eventually kill them.

Because of this, the ammonia contained in the water in the fish tank must be diluted, removed or converted. To find out the concentrations of ammonia within the fish tank, the water must be tested at least once a week using test kits.

We want our system to be

  • High in Nitrates
  • Low in Ammonia and nitrites

High levels of ammonia are mainly caused due to having overfeeding the fish or low aerobic activity of nitrifying bacteria. This can be caused due to a lot of factors like unstable pH, inadequate DO and temperature.

Check more about the role of ammonia in aquaponics

There can be a lot of factors that increase the ammonia and nitrite levels. If not treated they can cause nitrite poisoning.

Check here how to avoid and treat nitrite poisoning

When these are low (<15 mg/L) nitrates, there is probably some denitrification occurring; when this occurs, we use the DO meter to find low DO spots, which must be corrected.

11. Have you considered switching to a trickle gravel system?

Our research has found these are more efficient systems that are easier to maintain.

12. ignoring organic certification?

On the commercial level, having an organic certification matters a lot. Organically certified vegetables sell for between $3 and $4 per pound. Prices are the largest determinant of profitability.

13. Adding fish before the system has cycled

One of the most common mistakes I see in aquaponics with beginners is rushing to introduce fish into their systems.

Ammonia and nitrites produced from fish waste are toxic to fish. This can lead to pH and ammonia spikes and possibly death of fish. You need to cycle the fish to setup the system.

There are two ways of cycling your aquaponics system!

You can do it with fish or without fish.

Check out here how to cycle aquaponics system with fish

Check out this post to know how to cycle aquaponics system without fish

14. Poor circulation = poor oxygen content

Ensure adequate aeration and water circulation. This means you should use water and air pumps to make sure that the water has high levels of dissolved oxygen and good water movement so that your animals, bacteria, and plants are healthy.

Check this post to know more about the role of dissolved oxygen in Aquaponics

Remember: Electricity costs are a significant portion of the system budget so choose the pumps and power source wisely, and consider photovoltaic power, if possible.

15. Choosing the wrong fish!

You not only have to consider your space, seasonal conditions, budget but also the temperament, size, growth rate and diet of fish before thinking of keeping them.

You can’t think of using tropical fish in snowy areas! It is always recommended to choose a native fish which goes well with climatic conditions of your area. Even then you may need to keep the temperature in range. You’ll need aquarium heaters to maintain the temperature range of some fish in winter.

Read in detail about factors to consider while choosing your fish to choose the best fish for your aquaponics system.

16. Not maintaining the balance between plants and fish (fish to plant ratio)

Goldfish with mint
Plants to fish ratio

Having too many fish in the system will not only kill them but also may over-fertilize the plants killing them.

Different fish species will have different tolerances in this case and striking a good balance between fish tank, number of plants and the system’s total volume of water.

Maintain a balance between plants and animals, otherwise, either of these will not work rightly.

Using a batch cropping system can help keep a steady harvest of both aquatic animals and vegetables to keep a consistent production level and maintain a constant balance between fish and plants.

 Remember: A secure source of young plants and young fish is important, so make sure that the supply is considered during the planning phase.

17. Not using Timer or right-sized Water pump

Most beginners don’t choose a right-sized water pump. The results can be devastating to fish and plants’ health. You need to consider the water volume and height between the plants & fish container. Also, using timer along with pump will help you to set an automatic on/off cycle.

Check a detailed post about water pump setup here

18. Not choosing the right fish tank

Choose the tank carefully. Fish tanks are a crucial component in every aquaponic unit. Any fish tank will work, but round tanks with flat or conical bottoms are recommended because they are easier to keep clean.

Remember: Try using strong inert plastic or fiberglass tanks, because of their durability and long lifespan.

19. Overfeeding the fish and not removing uneaten food

Avoid overfeeding, and remove any uneaten food. Wastes and uneaten food are very harmful to aquatic animals because they can rot inside the system. Rotting food can cause disease and can use up all of the dissolved oxygen.

Remember: Feed the animals every day, but remove any uneaten food after 30 minutes and adjust the next day’s portion accordingly.

20. Using duckweed as an alternative to fish food!

Aquaponics is all natural and organic! Only input it needs is the fish food.

But some new growers/fish keeper go beyond it and may want to use duckweed as an alternative to fish food.

We’ve even seen claims that duckweed is around 40% protein and that it is the perfect diet for those trying to grow a high protein fish.

Yes, fish, specifically tilapia, will eat duckweed with gusto, and yes the duckweed will repopulate faster than the fish can eat it. It’s this info that makes it very attractive as a feed to fish to aquaponic growers..!

duckweed and aquaponics
duckweed

Let’s clear the facts on this note. Duckweed is 95% water. and duckweed isn’t a complete diet for Fish!

Duckweed does contain somewhere between 35-40% protein when DRIED.

Most of those that are advocating duckweed are unaware about this complete fact.

Your fish in aquarium/tanks are not eating dry duckweed. Your fish are eating wet duckweed which is 95% water. Which means that the protein content of duckweed is only 2%. (35-40% of the remaining non-water portion of wet duckweed)

This is why fish eat it so ferociously, it is because they are starving.

This is especially true of growers who try to rely solely on duckweed and don’t provide any supplemental nutrition to their fish.

Couple this with the fact that duckweed grows faster than your starving fish can eat it.

The growth is unstoppable and this is a problem. It gets out of the fish tank and into your pipes, grows beds, sump, pumps etc. It is unruly and can cause a major headache.

If you are interested in growing food for your fish look into insects. They provide more protein and won’t clog your pipes and pumps like duckweed will. Check how you can make healthy food for your fish at home or include free & protein-rich insects feed in your fish diet


Aquaponics is really easy, interesting and sustainable if you have enough knowledge about it.

Mistakes can be avoided easily if know about them. We have tried to list out all the mistakes that are made in aquaponics. So no more delaying it’s time to go out and try it out yourself!

Did we miss any mistakes that people make in aquaponics? or were you making any of these? Do tell us in comments

 

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