First determine the severity of the iron deficiency, because this will affect the way the iron is added to the system. If the deficiency is severe and is causing problems to the health of the plant, it is recommended to supplement iron by spraying it directly on the leaves, this will add a more concentrated dose to quickly help the plants recover from iron deficiency. Supplementing the tank with iron is also a good choice. High pH level can make it hard for the plant to absorb iron that is available in the system, having a balanced pH level can help quickly recover from the effects of iron deficiency. Chelated iron is recommended for aquaponics systems because it dissolves in water. It is important to know the difference between EDTA and DTPA, DO NOT use EDTA, as it is a toxic weed killer, while DTPA is an effective fertilizer and easily dissolves in the water.
Amount of Iron Needed to be Added to Treat Iron Deficiency
Method 1 (without meter): The standard recommended method is to dose 2 mg/liter of water and 7.58 mg/gal of pure iron every three weeks. You also need to check on the percentage of iron in the product you are using. Most of the iron supplement products are only a percentage of iron, it is recommended to you use a product with 10% iron, with 10% iron you must add 76 mg of iron to every gallon of water every three weeks.
Method 2 (requires meter): This method is more accurate, first you need to measure the current iron level in your system and then apply the following formula:
Desired iron level -actual ppm reading += amount of iron to added (ppm)
Amount of iron to be added (ppm) x (100. percentage of iron in supplement) = mg/liter.
Example:
A system with 100 gallons has an iron measurement of 1.9 ppm. (Using chelated iron with 10% DTPA)
So, 2.5 ppm – 1.9 ppm = 0.6 ppm
0.6 ppm x (100/10) = 6 ppm or 6 mg/liter
100 gallons = 378 liter
378 x 6 mg = 2268 mg or 2.268 grams of iron need to be added to the system.
Preventing Iron Deficiency
It’s common for established systems to need additional iron from time to time, as both fish and plants need iron for their health.
Regular monitoring and testing the water will ensure the system is balanced and healthy.
You can set a regular iron supplication schedule, such as adding iron every two or three weeks.
