# EI Calculator - Is it correct?



## gabriel.basso (24 Oct 2017)

Hey guys, how are you?

I'm starting to dose EI on my tank and got a little confused using Rotala Butterfly calculator.
My tank has 180 liters (49 gallons), but I considered only 126 liters (70%), since it has a very high slope, a lot of substrate, woods and stones.

To get the results I considered then 126 liters, a solution of 800ml, and 40ml per dose.
I made a spreadsheet compiling the results:




 

The calculator shows me the results based on these targets:
- NO3: 7.5ppm per dose / 22.5ppm 3x per week
- PO4: 1.3ppm per dose / 3.9ppm 3x per week
- K: 7.5ppm per dose / 22.5ppm 3x per week
- Mg: 5ppm per dose / 15ppm 3x per week

At this point I already noticed a slight difference between these targets and what I found here in UKAPs posts as a weekly ppm reference:
- NO3: 20ppm
- PO4: 3ppm 
- K: 30ppm
- Mg: 10ppm 

Initially for the macro solution I was thinking of dosing only KNO3, KH2SO4 and MgSO4, but in the end I would have a lack of K, only 15ppm per week when the target is 30ppm. So I added K2SO4 to the list to reach the target.

Therefore I have some questions:

- Are those Rotala calc results correct?
- The amount of Mg to be added into a 800ml solution for a 126 liters tank is really 575mg (0,57kg)?!!!
- Am I correct adding K2SO4 to the solution to reach K target?

Sorry for my english... its not my native language but I hope you will understand.

Thanks!


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## John S (24 Oct 2017)

When you put your aquarium size in are you sure you selected 126 Litres and not US Gallons?


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## gabriel.basso (24 Oct 2017)

John S said:


> When you put your aquarium size in are you sure you selected 126 Litres and not US Gallons?


Yes.. sure I put in litres. 

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## John S (25 Oct 2017)

I've just run the calculator for KNO3, 800ml bottle, 40ml dose and 126 Liters with a result of 30.82g to add to the solution.
I then run it with 126 US gallons and get 116.65g which is what you have in your original table?


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## gabriel.basso (25 Oct 2017)

John S said:


> I've just run the calculator for KNO3, 800ml bottle, 40ml dose and 126 Liters with a result of 30.82g to add to the solution.
> I then run it with 126 US gallons and get 116.65g which is what you have in your original table?


OMG I can't believe I did that  Feeling dumb right now. 
Thanks John, and sorry for wasting your time.


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## gabriel.basso (25 Oct 2017)

Well, after the initial lack of phosphate in my brain , follow the correct values:





So there are still one answer pending:
- Am I correct adding K2SO4 to the solution to reach K target? Most of the EI recipes I see doesn't mention K2SO4, but I guess it will be necessary to achieve 30 ppm.


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## ceg4048 (25 Oct 2017)

gabriel.basso said:


> Am I correct adding K2SO4 to the solution to reach K target?


No.



gabriel.basso said:


> Most of the EI recipes I see doesn't mention K2SO4


Correct.



gabriel.basso said:


> but I guess it will be necessary to achieve 30 ppm


This is what happens when people get caught up with numbers instead of trying to understand the basic principles.

Gabriel, please keep in mind that there is no precision involved in EI. This is specifically why it is called The "Estimative" Index. We are simply estimating the maximum amount of nutrition that the plant will ever need under the worst conditions.

When I look at these calculators and their orgy of numbers I feel a wave of nausea. 
T. Barr came up with a simple idea to avoid malnutrition in plants and people have perverted it into various flavors of bubble gum.

There is no precision involved here. There is no need to account for your gravel or rocks. Just call it a 50 gallon tank.
If you study the EI Tutorial you will see that I simply use numbers like 1/4 teaspoon - which no one can measure precisely.
I specifically avoid number of grams. It simply isn't necessary and your plants will never benefit from any level of precision.

There is a vast range of nutrient values that will satisfy the needs of the plants.
Folks are just wasting time and energy filling out spreadsheets when they should be concentrating on understanding the basics.
Do not become mesmerized by "target numbers".
EI and PMDD were developed at a time when the world was using "Zero ppm" as their nutrient target.
So if you are off by 20% or 50% you are still fine and your plants will tell you if you need to add more.

Cheers,


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## John S (25 Oct 2017)

gabriel.basso said:


> OMG I can't believe I did that  Feeling dumb right now.
> Thanks John, and sorry for wasting your time.


No problem, we've all been there

Clive has beaten me too it but I was just about to point you in the direction of this as you are not the first person to question the details:
https://www.ukaps.org/forum/threads/ei-newbie-totally-confused-lol.16457/


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## gabriel.basso (25 Oct 2017)

ceg4048 said:


> No.
> 
> 
> Correct.
> ...


Hey Clive

Thanks for your reply. I read this forum a lot for a long time and your posts are the ones I pay attention the most. By the way the thread "EI Dosing using dry salts" was the one that encouraged me to dose EI in my tank. 

I alredy got that there's no need to be exact on EI. And that's what I like the most on this method. I'm a lazy guy who likes simplicity. I don't intend to weight the dry salts every time to make the fert solutions at all. I'll use tsp tbs etc. I just used the rotala calc to show me the amounts I would need of each salt and round it up in table spoons.

But I must admit that 50% difference of K between the "target" and what the calc showed me really made me think something should be done. If you are telling it is not relevant ok, I'll trust your advice. 

In the end my approach will be to start dosing and let the plants show me on a weekly basis if that ammount of ferts is enough or not. 

Cheers


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## gabriel.basso (25 Oct 2017)

John S said:


> No problem, we've all been there
> 
> Clive has beaten me too it but I was just about to point you in the direction of this as you are not the first person to question the details:
> https://www.ukaps.org/forum/threads/ei-newbie-totally-confused-lol.16457/



Thanks a lot John. I'll read this carefully! Hope some day I have the chance and knowledge to beat some newbies a**es around here. LOL

Just kidding. I'm here to learn, just that. 

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## ceg4048 (26 Oct 2017)

gabriel.basso said:


> But I must admit that 50% difference of K between the "target" and what the calc showed me really made me think something should be done. If you are telling it is not relevant ok, I'll trust your advice.
> 
> In the end my approach will be to start dosing and let the plants show me on a weekly basis if that ammount of ferts is enough or not.


Yes, that is an excellent approach. 
EI is interactive and is very flexible. It is an idea, not a number.
If you observe that the plants need more, then simply add more.
If you can get away with less, then add less.
There are instances where hobbyists dose EI levels of nutrients and still get nutrient deficiency symptoms.
When this happens it is necessary to investigate the flow distribution, so you should be mindful of that possibility.
If flow/distribution is a problem then it is also likely that the plants will also suffer CO2 related deficiencies.

So be very careful when you attempt to determine what the plants are showing you.

As far as K goes, acceptable values is a wide range, from about 10ppm and on.
It depends on the level of lighting stress. Under maximum stress 30ppm is a better number than 10ppm. Even so, if you wanted to add more K then it can easily done by simply adding more KNO3. This simplifies the dosing. No need to look for another salt. That explains why you do not see other recipes using K2SO4.

K2SO4 was used because people were afraid of NO3, so they looked for a K salt that did not contain NO3. 
We know now that NO3 is not a problem, so really, K2SO4 is redundant.

Cheers,


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## gabriel.basso (26 Oct 2017)

ceg4048 said:


> Yes, that is an excellent approach.
> EI is interactive and is very flexible. It is an idea, not a number.
> If you observe that the plants need more, then simply add more.
> If you can get away with less, then add less.
> ...


Understood, thanks Clive!

I won't use K2SO4 then. Just increase a little on KNO3. 

Regarding the plant readings I'll have to learn on the fly, asking, making mistakes and so on. But I'll get there. 

Cheers

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