The Estimative Index

 Tom Barr describes the Estimative Index as “a simple method to dose nutrients for any tank without test kits. In a nut shell, the aquarist doses frequently to prevent anything from running out (plant nutrient deficiency) and does large weekly water changes to prevent any build up (Plant inhibition). In this manner, we can easily maintain a close approximation or an “estimation index” of the nutrient levels during the week, not too high, not too low and…..no need for a test kit because the accuracy is close and in most cases closer than a test kit.”  

But What Does That Mean?

The basic premise is that we dose macro nutrients on odd days and micro nutrients on even days followed by a major water change to “flush out” any excess nutrients which may have built up during the week.  You can read the full Estimative Index article here:  http://www.barrreport.com/forums/showthread.php?t=1

This strategy is based on the concept that we are going to dose a maximum amount of macro and micro nutrients that our plants will need – in order to make sure that we do not “run out” of nutrients and thus experience a deficiency.

So how do we “do” this Estimative Index dosing strategy?

It’s called the Estimative Index  because each day the aquatic hobbyists simply adds a set amount of micro nutrients (traces) and macro nutrients per 20 gallons of tank volume followed by a weekly water change.

If the tank has less plants, low light, this can/may be reduce in frequency but not dosage.

Tom writes:  “You can extend this method out to include all the other nutrients like traces and PO4 even KH and GH. You can try whatever you feel is "perfect" for plant growth and experiment around. Good sized weekly water changes are an excellent way to do this and avoid build up and any **dosing** errors or **testing** errors.”

So how much do we dose for a 20 gallon aquarium with high light?

Since the Estimative Index is based on a premise of dosing a maximum amount of nutrients that our plants could need – Tom recommends the following for a 20 gallon aquarium with 5.5 watts per gallon of light (boy is that A LOT of light!!!!).

That is all there is to it … dosing the Estimative Index approach can really be just that simple.  But if you need help, check out my Estimative Index in 21 Days email service.  For 21 days, I will send you an email message with a reminder of what needs to be done that day … can it be any simpler than that?  Click here to send an email message to start to receive your Estimative Index in 21 Days email reminders or simply send a blank email message to EIin21Days@GregWatson.com

But what if I don’t have a high light tank with 5.5 watts per gallon?

Tom recommends with the Estimative Index, that don’t have the super-charged turbo Ferrari style lighting like a 5.5 watts per gallon … we can simply dose less frequently or slowly back off the dosing amount until you notice plant growth slowing.

I still just don’t get it?

That’s ok.   Let’s talk about Plant Nutrition 101.

Plant Nutrition 101

Plants need a well balanced diet of Light, Carbon, Macro Nutrients, and Micro Nutrients.  The more Light you have, the more CO2 your plants will demand, and if they have enough CO2, the more Macro and Micro Nutrients they will need.

Light plus Carbon plus Macro Nutrients plus Micro Nutrients

Thus Light and Carbon are the gas pedal …

If you have an aquarium with 5.5 watts per gallon, your plants are going to demand a LOT of CO2 … and if they have enough CO2, they will also need a lot of Macro and Micro Nutrients.

If you have an aquarium with 1.0 watts per gallon, your plants are going to demand less CO2 and somewhat less Macro and Micro Nutrients.

Just like driving a turbo charged Ferrari on a gravel road … if you run out of anything you are likely to crash and burn … thus the Estimative Index is focused on making sure that we do not run out of our Macro and Micro Nutrients …

The Estimative Index Isn’t Working For Me!

If you are following the Estimative Index and it just isn’t working, then you are likely coming up short somewhere.   The Estimative Index makes the assumption that you have adequate CO2, and in most cases the nutrient deficiency is showing up in the form of not enough Carbon (or CO2).

So what is this “The Estimative Index in 21 Days”