# EI ratio



## andeekaii (1 Jun 2010)

Hi,

I was just on James planted tank, calculating how to make my EI mixture.
I've noticed that by adding the ammounts he says, that i cant get potassium up to anywhere near 30ppm.

I have 180 litre tank, and i wanted to dose:

KN03 - 60g per 250ml @ 10ml 3x per week = 24ppm Nitrate & 15ppm Potassium (per week)
KH2PO4 - 10g per 250ml @ 10ml 3x per week = 4.5ppm Phosphate & 1.8ppm Potassium (per week)

Which equals:
Nitrate @ 24ppm / week
Potassium @ 16.8ppm / week (Is this a sufficient amount? I'm going for a high tec co2 tank)
Phosphate @ 4.5ppm / week

I was going to also add

K2SO4 - 50g per 250ml @ 10ml 3x per week = 15ppm Potassium

This would bring the total up to 31.8ppm / week, is this correct?

Also, i've noticed magnesium, but none of the EI guides mention adding it? Is this added by manganese in the trace elements or is it usually in the tap water. Am i likely to see plant deficiencies if this level is correct?

Cheers, Andy


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## JamesC (1 Jun 2010)

Generally speaking there is often a fair amount of potassium in your tapwater so you don't normally need to add any more to the standard EI dosing. The 30ppm level is normally the amount you want and not how much to dose each week. So adding 15ppm per week and doing 50% water changes will result in a tank level of 30ppm after a few weeks. If you want to add more then it won't do any harm and then amount you suggest is fine.

Depending on where you live you may or may not need to add extra magnesium. I'm in Kent and have to add magnesium. Plants in my garden also suffer severe magnesium deficiency unless I dose them up with epsom salts. Best place to buy is eBay, I just brought 3kg for 98p. Adding an extra 5ppm Mg a week is a good level to start at.

Manganese is a different metal element and has nothing to do with magnesium.

HTH James


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## andeekaii (1 Jun 2010)

So If i add:

KN03 - 60g per 250ml @ 10ml 3x per week = 24ppm Nitrate & 15ppm Potassium (per week)
KH2PO4 - 10g per 250ml @ 10ml 3x per week = 4.5ppm Phosphate & 1.8ppm Potassium (per week)
K2SO4 - 50g per 250ml @ 10ml 3x per week = 15ppm Potassium (per week)

The first week the tank would have around 30ppm of potassium (minus whatever the plants use)
Then 50% water change would half that, so roughly 15ppm, then adding another 30ppm would make 45 (obviously minus what the plants use still)

If i keep this up for a long period of time could it result in an overdose (especially nitrate)
Or will a fully planted tank likely use the majority of what is being added. Then i just have to work out just how much and alter the dosing accordingly?

Thanks for your help by the way.
Andy


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## JamesC (1 Jun 2010)

This calculator works out how much build ups you get when adding ferts - http://www.ukaps.org/forum/viewtopic.php?f=11&t=10937.

If you do weekly 50% water changes then it's impossible to get double your weekly dosing levels. If you carry on the maths you were doing for several weeks you'll see.

James


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## andeekaii (1 Jun 2010)

Ah that's that sorted then.
Just ordered the 1kg of epsom salts for Â£2.49 delivered.

Is there anything else I should alter before i make my first batch?
Is aiming for 24ppm of nitrate okay I should i am for closer to 30?

Andy


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## JamesC (1 Jun 2010)

Seems good to me. All you need to worry about now is CO2 and flow.

James


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## andeekaii (1 Jun 2010)

I used the numbers from your dosing caculator to create the following:







If anyones interested maybe we could work together so I can implement a "tank size" into it, as I just used the ppms based on my 180 litre tank, but if you give me the calculations i could impliment tank size into the spreadsheet, tidy it up and maybe release it to the public?

But either way, it helped me figure out exactly what i'm doing/dosing/buying.

Cheers, Andy


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