Let’s see why, how and when to add minerals in aquaponics.
“Essential” minerals are known to be important for the plants development.
The most crucial ones are called “Macronutients”. We generally put the following in this category: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), magnesium (Mg), carbon (C), oxygen(O), hydrogen (H).
Others called “Micronutrients” or “Trace minerals” are needed in lower quantity. They are: iron (Fe), boron (B), chlorine (Cl), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni).
Minerals availibility in nature
In a classic garden, the worms constantly mix the deep soil with the surface and raise minerals to the surface. This action brings the macro and micronutrients available for the fungus, bacteria and plant roots.
Minerals availibility in aquaponics
In aquaponics we don’t have this link between deep soil/rocks and the ecosystem. We rely on the fish food added to the system only.
The fish food profile is different between brands but is generally high in nitrogen, Phosphorous, Potassium. But rarely covers all needs of the plants. Unfortunately the worms and fungus are not able to have access to rocks and make them available to the plants. A good way to fix this situation is to add rock powders into the system.
How to add minerals in your system
This can be under the form of rock dust or more elaborated mineral element powders. It will allow the life of the aquaponics system to have access to all the minerals needed for the plants.
The quantity to add is difficult to evaluate. I generally recommend 2mg/1000L or growbed square meter. The frequency is also tricky to evaluate. Some aquaponics growers like to add the powder once a month.
I personally prefer to add it when I can see the first signs of deficiency on my plants. In winter I run the system for months without adding any mineral but in summer I generally add some every other month.
The special one…
There is one mineral that is very quickly oxidised in aquaponics due to the moist and aerobic (in contact with oxygen) environment and this is the iron. Iron turns into rust none available for the plants. The best way to regulate this problem is to add chelated iron. It is a special iron encapsulated in another particle.
You will probably be interested to discover Jonathan’s six steps to build and manage an Aquaponics system. Click here to access for free! Thanks and good reading 🙂
