Just like humans, plants require food in the form of essential nutrients to grow and thrive. There are 17 key chemical elements that a plant needs to grow productively, and these can be broken down in Macronutrients and Micronutrients. Most commercial fertilisers will have the acronym NPK on the bag, this value explains the amount of available nitrogen (N), phosphorus (P) and potassium (K) in the formulation.
Macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, sulphur, calcium and magnesium. Micronutrients are needed in extremely minute amounts, and these include zinc, boron, manganese, molybdenum, copper and zinc. A lot of these elements will be available to the plant in soil but in hydroponics, we need to add them to the water in the form of soluble hydroponic nutrients. One of the most frequently asked questions posed is how much food to add after the initial first dose of nutrients that are added to the Aerospring tank.
Once nutrients are added to the water, they’ll be available as salts, and they change the electroconductivity of the water. With the help of an EC Meter, we’re able to measure the amount of salts ie. Nutrients in the water. As the plants grow, they’ll be taking up water and the nutrients in the tank. It’s important to keep your water tank topped up to full to ensure a steady and constant nutrient uptake. So, when you add more water, use the EC pen to measure the amount of food in the water and then top up nutrients to your desired EC level. It’s important to set EC levels for your system according to your temperatures. A lower value is advised for warmer climates, a higher EC value for temperate ones.
EC however has limitations: while it will tell you the total amount of salts in the tank, it won’t be able to detect the amount of individual elements. Because we grow a variety of plants in one system, each of them has different nutritional needs and rates that they pull from the solution. Over time, some of the elements will accumulate while others will decrease in concentration. The best way to rebalance the nutrient concentration in your tank is to flush it periodically and we advise to do this no later than every 12 weeks.
PH is an equally important factor to monitor when growing hydroponically. pH stands for “potential hydrogen” and is represented on a scale between 0-14 (0 being most acidic, 14 being most basic). The term “nutrient availability” refers to the way each nutrient becomes available to plant roots depending on the pH of their environment. For the most part, the various elements in the nutrients become available to the plant root system between pH values of 5.5-6.5. If the tank solution becomes too acidic (<pH 5) or too alkaline (>pH 7), some of the elements cannot be taken up by the plant which causes deficiencies.
Adding nutrients to the tank acidifies the water somewhat which is why pH testing should be done after topping off with fresh water and nutrients. You can test via the old-fashioned litmus paper testing method or employ a digital pH reader. If your test determines that the pH needs adjusting, add a minute amount of either pH down (diluted phosphoric acid) or pH up (potassium hydroxide solution). Always add a very small amount, a few drops to begin with, then stir the water tank with a utensil.
After vigorous product testing, we’ve settled on one pen that can do the job best. The Aerospring Multifunction Meter can measure EC, pH and temperature values of your nutrient solution easily with the click of a few buttons. It takes the guesswork out of how much to feed your plants and is an essential tool to have when growing hydroponically. It’s important to calibrate the probes of the meters regularly to maintain accurate readings but this is easy enough to do with the digital calibration feature in the pen.
Over time, you’ll begin to dial into the needs of your Aerospring Garden and know when to add more water, more nutrients/food and how to manage your pH levels. Checking your tank and nutrient+pH values weekly is recommended. Practice makes perfect, so the more time you spend with your garden and plants, the better you’ll become at hydroponic gardening!