The first step in Hydroponics farming is to understand the difference between soil fertilizers, and the requirements of plants. Most growers are aware of soil fertilizers such as those called by numbers 19-19-19 and 20-20-20, but what does 20-20-20 really mean?
Does it mean 20% Nitrogen (N), and 20% Phosphorous (P), and 20% Potassium (K) is the N.P.K ratio?
No, it's not that simple.
It's, 20% Nitrogen (N) and 20% Phosphorous Pentoxide (P2O5) and 20% Di-Potassium Oxide (K2O). (Depending on the country of origin, these units change by continent)
This translates to the actual % of the N.P.K as follows.
20% Nitrogen (N), 8.8% Phosphorous (P), and 16.6% Potassium (K).
However, a good Hydroponic nutrient contains all of these plus all the other minerals required for healthy growth. They will also be in the correct ratio to each other, according to plant type, and stage of growth, e.g. Vegetative, flowering or fruiting stage.
The minerals required for good growth are as follows:
There are other minerals found in plant tissue when analysed, but for our purposes, these are the main requirements for Hydroponic growing, and the ones we have to monitor.
Hydroponics grower has to understand and make sure that the Hydroponics nutrients being used have all the above macro and micro nutrients needed by the plant in a proportion that is needed at various stages of growth.
Take for example, the above 20-20-20 fertilizer with 20% Nitrogen (N), 8.8% Phosphorous (P), and 16.6% Potassium (K).
Researchers have determined that a tomato plant in fruiting stage needs more Potassium than Nitrogen with N:K ratio of even 1:3. Using 20-20-20 fertilizer for tomato crop in the fruiting stage might not give the best yield when compared to a Hydroponic nutrient modified in a proportion to suit the crop need.
Hydroponic farming gives best results only when the grower gives nutrients in the right proportion suiting crop, stage of growth, water pH, EC, climate conditions etc.