You all know what aquaponics is: it is the coupling between the production of fish and the production of plants, all of this turns together and constitutes an ecosystem. But do you know that there is also what is called decoupled aquaponics which consists of putting a barrier between the two worlds and a flow of water that will only go in one direction!? This is what we will see in this article.

Understand the concept: coupled / uncoupled

Before getting to the heart of the matter, it is important to understand how the system works.

So you have your fish that you feed, which breathe and which make droppings. All this material, all this nitrogen is treated in a biological mechanical filter. And then this water full of nutrients will land in your grow box to grow your vegetables. Plants will filter nutrients, especially nitrogen. And this water will go back to a sump which is the lowest point of our system, to then return purified to the fish. This is the pattern we know and see the most on the internet.

So it is very virtuous to couple these two systems. Except that by coupling them, we have to make some compromises: on the temperature, on the pH, etc… This is how the idea of ​​decoupled aquaponics was born, which consists of decoupling the two systems to have optimal parameters on both sides while having an interaction between the two. Otherwise, of course, you are doing fish farming on one side and hydroponics on the other, which would no longer be aquaponics.

We will therefore separate the two systems

So you need to have two separate bins. On one side, you will have the aquaculture loop: pump from the sump to the fish, to the filters then, back into the sump and on the other side, you will have the market gardening loop pump in the sump which brings the water back into the hydroponic system and water return in the sump.

What will happen next is that the flow of water will be opened punctually from the fish towards the plants and only in this direction.

But what are the advantages of such a system?

The first advantage that has been more or less mentioned above is that all parameters are adjustable independently of each other. There are no more compromises to be made as in a coupled aquaponic system. What are the trade-offs? This mainly relates to the pH. For example, your bacteria like a high pH while your plants generally grow with a low pH. You can also have a different nitrogen rate in the fish loop compared to the horticultural loop. So why would we want that to have better productivity?

The second advantage is that we will be able to preserve the health of our fish. It turns out that in aquaponics, there are deficiencies that are inevitable. So you're going to add nutrients. You will obviously ask yourself each time if the nutrients you bought and put in the water are not going to be dangerous for your fish. Of course, no one has done the test since it is generally fertilizer for plants. In the same way, when you treat your pests on your plants, even if you use the most organic products possible, namely soap, milk, oil, garlic, etc. There will always be which will end up in the fish. In the same way, in the professional world, in hydroponics, chlorine is used a lot to disinfect plants because of the microorganisms that develop on it. So, in a closed circuit, if you put chlorine, your fish will swim in it.

The third advantage is that we can treat fish without consequences for our plants. So the reverse is true since the two loops are separate. If your fish are sick and you have to treat them with salt with other products, it will not affect your plants since the fish loop turns in its corner.

And finally, recent studies show that plant production in a decoupled system increases by 35-40%. All this for a comparable fish production. So we don't compromise on the fish, we produce as many kilos of them. And on the other hand, as you have optimized the parameters of your plant water as in hydroponics, you will increase productivity.

You can imagine that if there are advantages, there are necessarily disadvantages since aquaponics was still thought to be coupled.

So what are these little drawbacks?

Decoupled aquaponics will require much more monitoring than coupled aquaponics. That is to say, instead of testing one system and mastering one system, you will have to master two systems in addition to the interactions between each system. So obviously it's going to take more experience and more supervision. And when we are in a commercial environment, we want to do it in automatic mode with probes.

Then, the second disadvantage is that in fact, the sizing of the system will be much more complicated than coupled aquaponics. It is recalled that in coupled aquaponics, we are going to deduce a need for nitrogen per square meter of culture, which means that we are going to deduct a weight of food to be given per day, therefore a number of fish, and consequently a volume of water in a decoupled system is much more complex. Quite simply because it does not run in a loop because the fresh water that you are going to add will go into the fish tank and it will then be necessary to estimate the evapotranspiration of the plants in the horticultural loop to supply the flow of water from the fish to the plants and compensate with new water on the side of the fish.

The third disadvantage is that it is not very suitable for a small aquaponics system in your garden, especially when you are starting out. So it's something that will be adapted to farms and therefore commercial aquaponics: people who are very familiar with fish production, plant production and who know how to play between these two systems.

Conclusion

The first thing to know about this system is that today it is only used for commercial systems.

To date, therefore, in the world of aquaponics, there are two main parts which are: the commercial part with people who do decoupled aquaponics and domestic aquaponics in your garden or in your apartment with water. aquaponics coupled with passage. This allows commercial systems to be able to cheat since they can, for example, put very toxic products on plants without harming fish. In coupled aquaponics, it is impossible to cheat because the products will directly end up in the body of the fish and the latter will die.