Before we begin, lets brush up on some basics regarding nutrients.
Primary Nutrients are used in the highest quantities, and are required for plant growth and development. These are most common building blocks of the plant. The Secondary Macronutrients are equally important. The Micronutrients are also important but in smaller quantities, for growth and reproduction. All these needs are supplied by Hydroponic Nutrient Solutions.
The Primary Nutrients are Nitrogen, Phosphorous & Potassium (NPK) These are the most important. Nitrogen for plant growth and reproduction and aiding in photosynthesis and proteins operating all through the cells. Phosphorous is important for the cell membrane. Potassium signalling root growth and reproductive development. These Nutrients are critical for plants production and growers who want to maximize plant production. It’s also critical that your measurements are done accurately, this directly affects your plant growth.
Secondary Macro-Nutrients like Calcium, which bonds cell walls, a structural element, like plant bones. Magnesium is important in photosynthesis, growth and reproduction and Sulphur are very important for plant health.
The Micronutrients are also absolutely critical. Without any one of them the plant will die or will only survive for a certain number of generations.
EC in you soil
We measure nutrients with Electrical Conductivity (EC). This entails putting two probes in the water and passing a current between them, this indicates how many soluble salts are in the water, or how many Ions we have and how easily the current passes from one probe to the other.This is mostly in Milliohms, Microsiemens per centimetre, PPM is commonly used, but more for total dissolved solids and has a different measurement. We use milli-siemens per centimeter and going for around 1.2’s for plants that don’t like a lot of salt or use a lot of water, up to the low 3’s for crops that are salt tolerant, and that we want full of Nutrients. EC is a simple measurement of a complicated thing. All modern solutions are scientifically formulated and tailor-made for specific crops. By measuring the EC we can tell how much nutrition is actually there. This means one doesn’t end up off balance, so it is simple to tell if we need to add more nutrients to the water and when we have too much nutrients in the water. Your EC should be lower during flowering compared to veggitive stage. This is because at vegative stage your plant needs to absorb more nutrients in order to maintain and grow. While flowering it takes less energy and spends more time developing the flowers. Needing less nutrients to do so.
EC measures the amount of soluble salts in the water, the amount of fertilizer in the water, still variable and depending on a measurement called pH, which measures the acidity of the water. pH influences the solubility of each individual Nutrient. Make use of Grow Room SA’s pH absorption Chart which tells you what the levels the minerals should be. It is important to manage both EC and pH. EC puts the nutrients in the water and pH makes the nutrients available to the plants.
Optimal pH is typically from the low 5’s upwards. Some crops prefer a higher pH however, closer to 7. Nutrient uptake is optimised within this range. pH has to be adjusted up and down to get maximum solubility of the plant Nutrients. To achieve this you need pH Down and pH Up, typically pH Down is an Acid and pH is a Base, commonly Potassium Hydroxide.
Nitrogen (1st part), is very soluble, where Calcium-Nitrate (2nd part) is hard to dissolve. One can use hot water to aid in this. You need to be sure your dosing ratios are correct. Part 3, Epsom Salts is very soluble. Part A. has almost all the Nutrients in the solution, however we need a lot more Nitrogen than we get in part A., so that’s why we add Calcium Nitrate. Keep this separate for solubility issues. Magnesium Sulphate is the cheapest and best way to supply Magnesium to the solution.
The easiest way to figure it out is to take the manufacturers word for it, you may tweak it or change it a bit for your set-up. Measure out the correct ratios into 3 separate buckets of water, (I mix part A. and part C. together, both are very soluble). Mix part B. in a separate bucket with warm water. Use your metered pump to get the exact amount of solution from each bucket into the main solution. If you are hand dosing it will be different.
You should be calibrating and checking often, if you are hand-dosing you should be measuring your pH and EC regularly. Measure EC first and adjust, then the pH, and measure throughout, and at the end.
To measure EC, get a hand-held analog measuring device or hand-held testers. To test pH you use color-metric tests, where you drop it into a solution and a chart indicates the pH or use Litmus paper.
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