Macronutrients and micronutrients

If you want to be successful with growing aquatic plants you have to provide them all necessary nutrients. Your planted aquarium is not a nature but it’s only a closed part of the nature. What does it mean? You have to supply these nutrients synhetically. In these articles I will try to explain differences between all kinds of nutrients which are key for successful growth of water plants in your aquarium.

We can divide nutrients into two large groups. Macronutrients, which plants need in higher amounts than micronutrients. On the other hand, micronutrients are very important too, because plants need all kinds of nutrients and if there is a shortage even of one of the nutrients, plants won’t grow. Plants need all nutrients.



Let’s check out, which macronutrients are the most important:

Macronutrients include carbon (C), which you can’t supply through any dry fertilizer. Plants capture carbon from CO2. Thats why a lot of people using CO2 pressurized cylinders and supply CO2 artificially to their tanks.

Oxygen and hydrogen are also macronutrients. But don’t worry about them. These two macronutrients are present in water – H2O. So we don’t have to supply them artificially.

Here starts the problematic nutrients. First one is a nitrogen (N). There is often a shortage of this nutrient in our aquariums. Especially when we have a strong lights. But solution is easy. You can add a specific amount of Potassium Nitrate (KNO3) weekly and everything will be ok.

Another important nutrient is phosphorus (P). Phosphorus is often in deficiency if you have just a few fish. Fish produce a waste and this waste is decomposed to phosphorus. Unfortunately, it’s hard to say, if you have enough of this nutrient, so it’s better to add some extra phosphorus in form of Monopotassium Phosphate (KH2PO4).

Potassium (K) is not included in water because it is removed in water companies. It is important to add some of this nutrient artificially. Some of K is in potassium nitrate, but it’s good to add some extra of it from Potassium Sulphate (K2SO4).

Magnesium (Mg) is last important macronutrient which is necessary supply through fertilizer. Especially if you have soft water, it’s very important to use Magnesium Sulfate (MgSO4) or MgSO4x7H2O.

Finally, it’s good to mention last two macronutrients. Sulphur (S) and calcium (Ca) are present in water in sufficient amount, so there’s no need to add them artificially.



Let’s take a look at micronutrients. They are called micro because plants don’t need them in such a high amount but you can’t overlook them, because without them the growth of plants would be stunt and unsightly.

Most important micronutrients are: iron (Fe), magnese (Mn), chlorine (Cl), copper (Cu), boron (B), molybdenum (Mo), cobalt (Co), nickel (Ni).

These nutrients are usually contained in conventional aquarium fertilizers like Seachem, Tropica etc. But you can also use dry fertilizer to supply micronutrients. You can use tenso cocktail or CSM+B. It doesn’t really matter which one. All liquid fertilizers are made from these dry salts, so it is senseless spend a lot of money for these comercial liquid fertilizers, if you can make your own liquide fertilizer from dry salts. It’s much more cheaper.