Estimative Index (EI) Dosing Method: Comprehensive Guide For Planted Aquarium Fertilizer Dosing

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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 good 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.

Renowned aquarist 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.

What is EI Dosing Method

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 14-15 ppm 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. (Just for your information, HC Cuba is considered as one of the most demanding aquatic plants in this hobby)

EI Dosing Ranges For Macro & Micro Ingredients

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

Ei Dosing Range For Macro And Micro Ingredients

Conditions of EI Dosing

  • There must be at least 70% area 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

Dosing Schedule

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:

First Example

1st Example Of Ei Dosing Schedule For Mid Tech Planted Aquarium

Second Example

2nd Example Of Ei Dosing For Mid Tech Planted Aquarium

In both examples above, you can see that the macro and micro ingredients are split over the first six days of the week. There is no dosing on the 7th day, so that the plants can take up any excess nutrients in the water column. After that, at the end of the 7th day, we do a 50-70% water change to basically reset the parameters of the tank and start dosing again.

Why EI Dosing?

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 out-competes 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.

How to get EI-based Fertilizers?

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

IngredientSource
MACRONitratePotassium Nitrate (KNO3), Calcium Nitrate (Ca(NO3)2), Magnesium Nitrate (Mg(NO3)2)
PhosphateMonopotassium Phosphate (KH2PO4) or Dipotassium Phosphate (K2HPO4)
PotassiumPotassium Sulphate (K2SO4), Potassium Chloride (KCl),
Note: You will already get Potassium from KNO3/KH2PO4/K2HPO4)
CalciumCalcium 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.
MagnesiumMagnesium Sulphate (MgSO4)
Note: You will already get Magnesium if using Mg(NO3)2
SulfurYou will already get it from MgSO4/K2SO4
MICROIronPlantex 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 mot much of it can be absorbed by the plants.
ManganesePlantex CSM+B, Manganese Chloride (MnCl2), Manganese Sulfate (MnSO4)
CopperPlantex CSM+B
ZincPlantex CSM+B
MolybdenumPlantex CSM+B
BoronPlantex CSM+B, Borax Decahydrate (Na₂[B₄O₅(OH)₄])
ChlorideNote: No dosing needed. You will get additional Chloride if using KCl for Potassium.

Note: Only some of the options for ingredient sources are mentioned above. Using Plantex CSM+B will take care of most of your Micro nutrients without needing additional supplements in most cases. Other than Plantex CSM+B, there are other options too, like CO2Art Trace or GLA Micronutrients; but Plantex CSM+B is by far the most widely used one.

Are there any all-in-one EI-based commercial fertilizers?

If you don’t like the idea of mixing your own ferts at home then surely there are ready-made options. Listing them below for your convenience –

1. EI NPK + CSM + B w/Iron (Most widely used, a bit hassle for begginers)

2. Thrive/Thrive+ (Easy and convenient, all in one bottle)

3. APT Complete (A very good alternative)

Final Thoughts

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 about this article, please let me know in the comments and I will try to clarify more on that issue.

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