All you need to know about Estimative Index (EI) Dosing

In a planted tank, fertilizers are very important. Plants need CO2, fertilizers and light for their growth. All three are important. And they need to be balanced. So, you cannot have like high light and high CO2 but low fertilizers. Similarly, you cannot have low co2 and low light but provide high fertilizers. But among these three items, CO2 is by far the most important, because how much co2 you have in your tank determines how fast and how well your plants will grow.

We all struggle to achieve a perfect balance of these three items in our tanks. Tom Barr came up with this idea of a high-energy tank with ample nutrients, so that you can achieve this balance easily. That’s where EI Dosing method came into being.

The concept is really very simple. First, you provide as much CO2 as possible in your tank. This is around 30-35ppm with pressurized CO2. However, with DIY CO2 (either citric acid+baking soda or yeast-sugar mixture), you can provide up to 14-15ppm CO2 in a tank that is no larger than 30 gallons. Using DIY CO2 in a tank larger than 30G cannot even provide enough CO2 to achieve the requirements of a mid-tech tank unfortunately. Secondly, you provide enough macro and micro fertilizers in the tank so that there is no deficiency of any of the 13 macro or micro ingredients. Now that your plants have as much CO2 as they need, and also as much nutrients they need, the only thing you have to tune to achieve balance is light. While using EI dosing method, light beyond medium is not required at all! Even if you are growing HC Cuba, if you have high CO2 and high fertilizers in EI dosing method, you can grow HC Cuba perfectly with medium light.

Below are the ranges typically maintained for the macro and micro ingredients:

  Ingredient EI Dosing Range
MACRO Nitrate 15 – 30 ppm
Phosphate 2 – 6 ppm
Potassium 20 – 30 ppm
Calcium 15 – 30ppm
Magnesium 5 – 10 ppm
Sulfur 2 – 6 ppm
MICRO Iron 0.5 – 1.0 ppm
Manganese Required in very small amount but needed nonetheless
  • There must be at least 70% are covered with plants. This should be done for any planted tank, regardless of what dosing method you are following. There is no point in dosing when there is not enough plants to uptake them.
  • You must have good amount of CO2 in the tank (around 15ppm for mid-tech and 30ppm for high-tech)
  • You must have good circulation/flow in the tank. The circulation rate is independent of your filtration rate. For example, in a 100-liter tank, you can have a filter that is running at 600L/H (6x) but your water circulation rate should be around 1,000L/H (10x). Water circulation is like blood flow inside our body as they carry the CO2 and the nutrients to the furthest corners of the tank. Also, good water flow helps keep the substrate free from debris buildup and makes maintenance easier.
  • At least medium light (around 3 watts per gallon CFL or around 1.8-2 watts per gallon LED)
  • At least 50% Water Change weekly

In EI Dosing method, the amount of fertilizer required is usually spread among 2-3 doses, instead of dumping it all at once. Also, macro and micro ingredients are usually dosed on alternate days. Below I will show two examples:

Example-1: EI Dosing Schedule for Low-Mid Tech
Nitrate 7.5     7.5     50% Water Change 15
Phosphate 1     1     2
Potassium 5     5     10
Sulphur 1.5     1.5     3
Magnesium   2.5     2.5   5
Iron   0.25     0.25   0.5
Example-2: EI Dosing Schedule for Mid-High Tech
Nitrate 7.5   7.5   7.5   50% Water Change 22.5
Phosphate 1.3   1.3   1.3   3.9
Potassium 10   10   10   30
Sulphur 1.5   1.5   1.5   4.5
Magnesium   3   3   3 9
Iron   0.25   0.25   0.25 0.75

There are many benefits of EI Dosing Method over the traditional ADA Lean Dosing Method. Below I will highlight some of the most important ones:

  • IT IS CHEAP! In many cases, it can be 10-20 times cheaper than using commercial fertilizers.
  • You have total control of how much of what ingredient is going into your tank. That eliminates any guessing. Most fertilizers available in the market does not even mention what ingredients are in there, let alone how much. So, you are practically dosing blindly, solely believing in what is printed on the label.
  • It actually reduces chance of algae attack. When there is enough nutrients for the plants to uptake, they grow strong and healthy and outcompetes algae so they cannot grow and take over the tank.
  • EI Dosing is proactive rather than reactive. In a lean dosing method, you wait to see if there are any signs of deficiency in the plants and then react by adding extra amount of that nutrient. However, any deficiency takes at least a month or more for the plants to recover from. With EI Dosing method, it is proactive as you are ensuring that all the required ingredients are already there in ample quantity so that the plants never face any deficiency in the first place.

You need to use dry salts and mix them in appropriate ratio to make your own. Below are the items usually used for this:

  Ingredient Source
MACRO Nitrate Potassium Nitrate (KNO3), Calcium Nitrate (Ca(NO3)2), Magnesium Nitrate (Mg(NO3)2)
Phosphate Monopotassium Phosphate (KH2PO4) or Dipotassium Phosphate (K2HPO4)
Potassium Potassium Sulphate (K2SO4), Potassium Chloride (KCl),
Note: You will already get Potassium from KNO3/KH2PO4/K2HPO4)
Calcium Calcium Carbonate (CaCO3)
Note: You will already get Calcium from Ca(NO3)2. Usually there is plenty of Calcium in our tap water so additional Calcium dosing is seldom needed.
Magnesium Magnesium Sulphate (MgSO4)
Note: You will already get Magnesium if using Mg(NO3)2
Sulfur You will already get it from MgSO4/K2SO4
MICRO Iron Plantex CSM+B or Ferrous Gluconate or Iron Chelate
Note: Iron has two forms, Ferrous (Fe II) and Ferric (Fe III). Only Ferrous state is acceptable for plants. However, that needs to be chelated. To “chelate” a mineral means to increase its absorption rate by binding it with a “chelator” or binding agent like EthyleneDiamine Tetraacetic Acid (EDTA) or DieThylenetriamine Pentaacetic Acid (DTPA). And that is why, though many places show to make DIY Iron Supplement using Ferrous Sulfate (FeSO4), it is very much ineffective and not much of it can be absorbed by the plants.
Manganese Plantex CSM+B, Manganese Chloride (MnCl2), Manganese Sulfate (MnSO4)
Copper Plantex CSM+B
Zinc Plantex CSM+B
Molybdenum Plantex CSM+B
Boron Plantex CSM+B, Borax Decahydrate (Na₂[B₄O₅(OH)₄])
Chloride Note: No dosing needed. You will get additional Chloride if using KCl for Potassium.

Yes! Aquartia is providing the ONLY EI-based fertilizers in the market today! All Aquartia fertilizers and supplements are made from only lab-grade ingredients to ensure the top-most quality and safety for your aquarium. Click here to buy now!

A lot of this can be new or intimidating to you. However, please understand, you do not need to be Walter White to understand this! It is actually very easy. Whether you will use EI dosing or not, I would like to encourage you to understand the concept of it at least, so that you do not go in blind and dose your tank without knowing what you are putting inside it. If you have any questions please let me know in the comments below.

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