British Columbia Aquarium Forums banner
1 - 20 of 35 Posts

· Dark Lord Owner
2,240 Posts
Discussion Starter · #1 ·
I know there are many people that do not know what this is.. or maybe they know a little bit... but arnt sure what to do.. or why you do it... Well i'm starting this thread for everyone to ask questions regarding EI dosing..

Basically your plants need food when you getting into med-high light tanks and start addiing co2.. nutrient uptake is alot greater than lets say a low light tank where just fish poop can help plants out...

Then all along came this guy his names tom barr, some may know him some not.. he's a legend and inspiration in our hobby, he's a scientist... pretty much and his hobby is aquariums.. he's been doing this.. for a long time.. and he came up with the concept EI (with others of course) to give plants a bit more nutrients then they need...then do a water change on a weekly basis to reset all the paramaters...

Here's a article from tom barr a bit about what it is.. and how you exactly do it.

The Estimative Index (EI) is a straightforward method for providing nutrients for a planted tank. The idea behind EI is simply introducing an excess amount of nutrients within an aquarium, throughout the week. This excess of nutrients floods the water column and feeds the plants. This is an estimative method; measuring specific nutrient uptake rates is not necessary and no test kits are involved. EI provides a surplus of nutrients that helps to prevents plant deficiencies, and allows plant growth unhendered. Most algae releated issues are due to plant deficiencies rather than excess nutrient levels(Ammonium/NH4 + is the exception).

Basically you add a slight excess of nutrients to prevent anything from running out, then do a large water change at the end of the week to prevent anything from building up. This allows you to maintain a range of nutrients without ever using a test kit.

The water change generally takes about the same amount of time once you haul out the hoses etc do the water change so the time and work difference between a 25 % and 50% water change is fairly small.

The process of which this is done is simple. Each day (or 2-3x a week, weekly for low light tanks) fertilizers are dosed, and the nutrients are absorbed by the plants. With this method being estimative, we can dose fertilizers according to general guidelines suited for our particular setup (see below for regime). At the end of the week, one performs a 50% water change to 'reset' the nutrient load in the entire system. And then the entire dosing regime is repeated. The hobbyists can do larger(which will afford more accuracy) or smaller water change routines, but 50% is just guide line.

The primary fertilizers are the macro nutrients - Nitrogen (N), Phosphorous (P), Potassium (K), and the micro nutrients - trace elements (Plantex CSM+B, Flourish, Tropica Master Grow-TMG). Iron (Fe) can also be supplemented if necessary.

The Estimative Index method works best for a high light and well planted aquarium. However it is not limited to higher light setups, smaller quantities of fertilizers can be dosed if low light is used. Also, the frequency may be reduced to 1-2x a week at low light(1.5-2w/gal).

How do I use the chemicals?

There are two ways in which you can dose the nutrients, by making a stock solution or by adding dry using a set of standard spoons. If making solutions then this is a guide to the amounts required.

Potassium Nitrate - 40g to 500ml of water and adding 10ml per 100L of water would give you a value of 5ppm.
Potassium Phosphate - 15g to 500ml of water and adding 5ml per 100L of water would give you a value of 1ppm.
Potassium Sulphate - 55g to 500ml of water and adding 10ml per 100L of water would give you a value of 5ppm
Magnesium Sulphate - 70g to 500ml of water and add 50ml once a week per 100L of water - this would give a target of 7ppm.
Trace mix - 15g to 250ml of water will give you about the same concentration as the 'off the shelf' products. It is also a good idea, if you can, to add 0.5ml Normal hydrochloric acid as this helps to prevent the chelator from breaking down. Some people complain of mould growing on top of the solution - keeping it in the fridge should help prevent this and prolong it's life.

It is possible to add the solutions into one bottle except for the trace mix as, depending on the chelator used, the iron could react with the phosphate. Generally speaking it is a good idea to make the solutions up in separate bottles until you are comfortable with the dosing.

nb. It is preferable to make up the solutions in RO water or Deionised water, but tap water can be used if need be.


This is a general dosing guide that can be used with the following tank sizes. Solution volumes are calculated on making the stock solutions as above. Tank volumes are in US gallons. To convert to UK gallons multiply these figures by 0.83

10-20 Gallons (38-76 litres)
10ml solution or 1/8 tsp KNO3 3x a week
5ml solution or 1/32 tsp KH2PO4 3x a week
2ml solution or 1/32 tsp K2SO4 3x a week
2ml or 1/32 tsp traces 3x a week

20-40 Gallons (76-152 litres)
20ml solution or 1/4 tsp KNO3 3x a week
12ml solution or 1/16 tsp KH2PO4 3x a week
5ml solution or 1/16 tsp K2SO4 3x a week
5ml or 1/16 tsp traces 3x a week

40-60 Gallons (152-227 litres)
30ml solution or 1/2 tsp KNO3 3x a week
18ml solution or 1/8 tsp KH2PO4 3x a week
8ml solution or 1/8 tsp K2SO4 3x a week
10ml or 1/8 tsp traces 3x a week

60-80 Gallons (227-303 litres)
40ml solution or 3/4 tsp KNO3 3x a week
25ml solution or 3/16 tsp KH2PO4 3x a week
11ml solution or 1/4 tsp K2SO4 3x a week
15ml or 1/4 tsp traces 3x a week

100-125 Gallons (380-473 litres)
70ml solution or 1 1/2 tsp KNO3 3x a week
40ml solution or 1/2 tsp KH2PO4 3x a week
16ml solution or 1/2 tsp K2SO4 3x a week
30ml or 1/2 tsp traces 3x a week

EI target ranges
CO2 range 20-30 ppm
NO3 range 5-30 ppm
K+ range 10-30 ppm
PO4 range 1.0-2.0 ppm
Fe 0.2-0.5ppm or higher
GH range 3-5 degrees ~ 50ppm or higher
KH range 3-5

See dosing calculators for additional dosing guides for Fe, etc.

Where to buy fertilizers?

So your next question might be ok well i figured it out kinda but where do i get these macro fertz. Well i got a secret for you. Rex Grigg is a guy that sells them to people living in the states and Canada and you can checkout his website right here. .

As far as the Micro (trace) you can buy those are your local fish store, you know the usual bottles that have trace elements.. seachem flourish

1 lb of each for Chemicals will last at least 1 year:

Plantex CSM+B
Potassium Nitrate KN03
Monopotassium Phosphate KH2PO4
Potassium Sulphate K2S04

Special Notes:

Providing optimal CO2 levels of at least 30 ppm are necessary for plants to prosper. If algae issue arise, remove all visible algae and infected leaves. Recheck CO2 levels, and possibly reduce and adjust the lighting period.

Direct dry dosing into the tank is perfectly fine. Many dose straight into, or they dissolve each daily amounts in water before adding. Plantex CSM+B is often mixed into solution for liquid dosing. 1 tablespoon to 250ml water is equivalent to: 20 ml = 1/4 teaspoon of dry Plantex. This solution is stored in refrigerators to prevent mold from forming within the container. HCL can be added to prevent the mold.

Small dosing teaspoons (smidgen, dash, pinch) can be found at Linen & Things, Bed Bath and Beyond, Wal-Mart, dollar stores, eBay and other online retailers. To identify the specific measurements of your smidgen, dash, pinch set, a 1/8 tsp should fill a ¼ tsp in 2 tries, 1/16 tsp in 4 tries, and a 1/32 tsp in 8 tries.

Sticking to a good dosing regime will make your plants flourish, and keep you delighted! If you seek more in depth discussion about EI, there are two other articles here.

John N and Tom Barr
If your thinking now.. heck where do i get these from.. well many plant stores around our area carry these, members on the site may want to just post if they have some for sale. Me personally i bought some off another member here a long time ago i just cant remember.

So Let me know any questions and i'll be glad and happy to answer, i'm sure everyone else will pipe up aswell.

Me personally i do this and it's worked for me... ever since i've done it... My plants show no signs of nutrient deficientcy like they used to and they grow fast.

· Registered
2,839 Posts
in regards to:
Trace mix - 15g to 250ml of water will give you about the same concentration as the 'off the shelf' products. It is also a good idea, if you can, to add 0.5ml Normal hydrochloric acid as this helps to prevent the chelator from breaking down. Some people complain of mould
You can also use Excel, about 10ml for a 250ml solution of csm+b to prevent the mold. its much safer to handle than the muriatic acid. For those with metricide, thats about 6 mL metricide per 250ml csm+b mix.

For those without the metricide/excel, you have other options, refrigerate the csm+b mix, and/or half the amount of csm+b in your mix and double the dose. Trick is to not make enough solution to last months, you want to get it down to being used up in 3-4 weeks.

· Registered
8,717 Posts
in regards to:

You can also use Excel, about 10ml for a 250ml solution of csm+b to prevent the mold. its a bit safer to handle than the muriatic acid. For those with metricide, thats about 6 mL metricide per 250ml csm+b mix.
Edited that for ya. It's not much safer, especially if you are using Metricide, which is double strength. I wouldn't want to get either in my eye.

MSDS on Metricide:

· Registered
2,839 Posts
i never implied metricide was safe to be careless with, in fact, the majority of chemicals in EI dosing are just as unsafe as metricide (or more unsafe). But you bring up a good point that MSDS's should be mentioned:

Muriatic Acid

and a relink for the metricide
Metricide The picture is missing on top, its the HMIS ratings, but its in section 11 on the msds, H1 F0 R0.

· Registered
68 Posts
i never implied metricide was safe to be careless with, in fact, the majority of chemicals in EI dosing are just as unsafe as metricide (or more unsafe). But you bring up a good point that MSDS's should be mentioned:

Muriatic Acid

and a relink for the metricide
Metricide The picture is missing on top, its the HMIS ratings, but its in section 11 on the msds, H1 F0 R0.
Actually they(fertilizers suggested) are far far from as toxic as Excel or this product. 4ppm is the lethal dosage for many inverts, and not much more, say 4-8ppm is the lethal range for most fish.

Never met anyone yet that's overdosed and killed any fish to date.
I guess if you add enough to get salinity or salt stresses..........
Same for GH booster........

Traces are equally as high relative to the needed dosing, but not absolute ppm's.

Still, you'd have to make Extremely gross errors.

Folks get very loose with dosing Excel or similar generics, then kill fish in their quest to kill algae. Rather than going about things slow and focusing on the root mismanagement issue. CO2 and Excel kills more critters than ferts ever have or ever will at least 10000 fold.

So care should be placed there, and less fear based myths placed on fert dosing.

Also, MSDS tells you little about the chemicals effect on the fish or inverts.
You need to look for a good article etc on that like this:

Now you have something a bit more applied and useful.

Tom Barr

· Registered
2,839 Posts
For those mixing a single macro solution up to do multiple small tanks and don't want to drop money on a scale, i pulled these numbers from rex griggs site

mass per tsp:
KNO3 = 5.6 grams
KH2PO4 = 4.8 grams
K2SO4 = 6 grams

using nicklfires ratios, 3:1:1 (N:p:K), taking 40 grams of nitrates and applying it to the ratio, then converting each teaspoons, i came up with these numbers
7 1/8 tsp KNO3
2 3/4 tsp KH2PO4
2 1/4 tsp K2SO4
per 500mL of Water.

i'd say 0.7mL per gallon. using the median for each EI dose range and the nitrate solution dosage, it comes pretty close to that :)

I could be wrong with these numbers, but i'll be giving it a try since with a couple small tanks its a real pain to measure dry doses without a scale.

· Registered
1 Posts
Many thanks for posting this ! Very helpful stuff !!

I am curious about the PO4 dosage.

From what I've measured, both Tom Barr's suggested dosage (original post) and neven's all-in-one mix seem to exceed PO4 by more than 3 times the recommended ppm.

For instance (using APC's Fertilator and Chuck's Calculator, same results), with Tom's dry dosage for 40-60G :

1/2 tsp KNO3 => 8.43 ppm NO3 + 5.31 K
1/8 tsp KH2PO4 => 2.58 ppm PO4 + 1.06 K
1/8 tsp K2SO4 => 1.90 ppm K

Weekly Total for 3 dose/week : 25.58ppm NO3 + 7.74ppm PO4 + 24.81ppm K

For neven's mix, I calculated: 25.21ppm NO3 + 11.93ppm PO4 + 27.95ppm K

NO3 is within range (5-30 ppm)
PO4 is over 3x above range (1-2ppm)
K+ is within range (10-30ppm)

Of course, E.I. is estimated and it doesn't matter if there are slight variations, so exact ppm do not matter here.

Still, I'm somewhat concerned about the ratio of PO4 compared to the other macros in all of the above... I think excess PO4 can trigger algae blooms (correct me if I'm wrong)

Please advise :)

· Registered
2,839 Posts
The joys of converting masses to capacity will always be a lack of accuracy to the numbers. If i had a scale i'd definately be using that and go directly from masses. But with EI theres room for error, and i've never had a massive algae bloom on an established tank doing EI dosing even with dosing more phosphates than i put in the mix (when i dry dosed)

Phosphates also can be tricky to really measure how much your tank has because its really dependant on how much you feed. Many people don't even need to dose kh2po4 because they feed enough food. People probably can get away with halving the phosphates in the mix, but if Green spot algae appears on plants, you may want to increase the phosphates the next batch.

· Registered
2,839 Posts
how much do you add for EI dosing for those of us using the standard off the shelf liquid ferts like seachem's liquid N, P, and K, i just ordered a 500mL bottle of each for my ebi
(oh and how much iron too? its this one Brightwell Aquatics Florin-Fe - 500ml - Pets & Ponds and i have some rosa nervis hygro that i would like to be its reddest)
if you use a booster like equillibrium then you do not need to worry about iron

If you use csm+b you do not need to worry about iron

as for EI dosing with off the shelf ferts, you'll be spending a lot of money since they are diluted. The information is on the bottle just how much is added with each dosage, using a calculator like fertilator will help you figure out where you'll be EI dosing

· Registered
157 Posts
I have a spiffy new spreadsheet for making batch macro liquid mixes. I find liquid is better, as you have more control over things (mainly phosphate). However, this is only if you obviously have access to a scale. I might make one for dry ferts. PM me if you want it!

· Registered
783 Posts
Sorry if this is a silly question, but I have 20G and I was thinking to mix all macro in one bottle and dose as liquid. Based on the info on previous page I came up with numbers:
200g KNO3 + 37.5g KH2PO4 + 55g K2SO4 and 500mL distilled water. Then dose 2mL 3x a week. I just multiplied measurements based on liquid dose recommendations. Could I do that? Or is there any other mix formula I should do? (add Magnesium Sulphate?) I've been dosing liquid mix based on the formula that has been recommended to me (by tim AF and confirmed by others) and it's not working for me. thanx

· Registered
8,717 Posts
So, what's the correct dosing scedule for Magnesium Sulphate? Its listed in the first part of the mixing suggestions and then completely disappears. Is it just for adjusting general hardness?
Yes, it's for GH and for Mg of course. Once a week or after every water change, if you do more than one wc a week, if the water is soft (which I believe it is in Coquitlam).

· Registered
68 Posts
This method seems incredibly wasteful and creates a lot of extra work.
Well, if you assume that you can never modify it and that it is written in stone, I've never stated that is, I think I should know a thing or two about it, hehe.
Common sense goes a long long way here.

If you chose a method to feed/dose/care routine for livestock/plants, then you should be adding a bit more than demand calls for. Discus folks and most all breeders and fish keeper sstuff their fish with food as much as they can. To off set all the growth and waste, they do frequent 2x a week water changes, some do them daily.
Do you hold the same view towards those folks in the hobby as well? Probably not.

But let's say you do and you want to reduce the % water and the frequency to reduce your labor.
What modification methods would you use to dial in the optimal dosing that waste the minimum amount of ferts/and requires the least water changes?
In otherwords, what is the best management practice(BMP's) once things are doing well?

Well, you'd start higher than demand, so you have independence. Plant Scientist do this with Hoagland's modified solution for fertilizers, EI does the same thing basically for aquatic plants.
This way you see only plants without any deficiencies.
If you start at the other end, you have no idea what the end point will be and many plants take a long time to recover from being limited.
So the upper bound is a much better starting place.

Next you progressively reduce the ferts stepwise over 2-3 week time frames.
Once you see a deficient plant response, you bump back up to the last prior highest dosing amount for that aquarium.

You've now hit what is called in agriculture, the critical point, or Cp. At this point you can reduce the water changes say down to once a month and maybe 25-40%. See the 70 Gallon below as an example that did this same approach.

Most of the work involved includes a wide range of nice plants, species and no algae, healthy fish and I sell about 500$+ a month in aquatic plants from this aquarium.
But I do more water changes, uprooting and generally making a mess if I did not do water changes frequently(2 x a week 50-60% here). So I use about 125 gallon of waste water to water the landscaping from this tank, and where I live, that's about 1/4 the daily high grade tap water used for landscape plant watering.
Lawns of grass? Now that's real waste, this is hardly any thing if you want to discuss ecological impacts or environmental concerns of this hobby.

This is really a false argument near as I can tell, I never see aquarist saying such things about Discus keepers.
Now the labor, that's a legitimate argument.
But there's many good effective ways to manage it.

This is my 120 Gallon tank I redid about 3 months ago. It's a high light stem plant dutch style tank. Lots of rare species, and I enjoy trying out various species and movign them around to see where they best are suited and what color contrast I like.
I might spend 2 hours a week on it. Of which is mostly water changes which while it drains/refills, I am trimming plants, it's multi tasking.


EI is not a method per se, it's a concept, you can modify it to reduce wastewater/reduce water changes % and/or frequency pretty easily.
Most hobbyists waste their light, which cost them far more than the water, which can be directed for other use, such as the lawn, which is FAR more wasteful than any aquarium ever could be in terms of water usage.

Now labor is quite another matter. But since that's an issue that you have raised, let me show you another tank that's quite different, and gets much less input and labor than any planted tank you have ever had.
Actually I'll show 2 tanks, one is a non CO2 method, the other uses CO2, but is still lower light and plant choice and locations have made a large difference in the amount of labor required, you will not have a nice Dutch high light tank and no labor, there is not such aquarium in existence.
I can offer folks trade offs.

But good horticultural skills can go to lower energy/input or a higher energy type system.

70 Gallon is much different, I might dose 1-2 x a week, and water change once a month.

In both cases, the tanks are modified from the original suggestion.
The suggest is just a starting point to modify if you have ther desire and skills, time to do so, if not, doing weekly 50% water changes is hardly bad advice for plants and livestock.
It is usually the snake oil purveyor that's trying to fool folks into no water change systems.

Sure many can get away with, myself included and without testing a great deal, but is that good general advice? No, not really, experienced folks, those with a very specific goal and idea? Then sure.
Aquariums are luxury items,a source for invasive species, wasting energy .....they are not some "ecological benefit". But we all like them here. It's a trade off we are willing to make.
Each method has trade offs and benefits. You do get to keep 12 Discus and feed them to the gills in a 20 Gallon tank and expect good large healthy fish, just as I cannot expect good results from the 120 if I do not keep up on good gardening and water changes.
EI is just an upper bound, so virtually all other aquariums will use LESS, so progressively reducing the ferts slow and methodically is a wise approach. I've never stated otherwise.
there's no need to lard it on and the plants are the ultimate test and the method is specific for every individual tank. The trade off and problem(and you know there is one here)? Many folks do not want test, many do not want to do the slow progressive method and many will not/do not observe and watch their tanks.
You cannot save or develop a method for everyone, even if you did, they invent a better fish and plant killing hobbyist :)
1 - 20 of 35 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.