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Discussion Starter · #1 ·
I have read basically 3 different recomendations here and there on the web when it comes to dosing dry MACRO ferts using the EI method and i cant seem to decide which is right !

1) One says all you need to dose is K2SO4 for macro's to get all the potassium (K) into your tank that plants need and that all the nitrogen (N) and phosphate (P) they need will come from fish droppings and uneaten food.

2) Another says that you only need to dose KNO3 and KH2PO4, and not K2SO4 because enough K comes from the KNO3 and KH2PO4.

3) And yet another says to dose all 3 (KNO3, KH2PO4, K2SO4).

Which of these are true ? :help:

James
 

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yeah i would kinda like to know... i dose all three personally...
 

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The answer is .....depends. I used to dose all three in my high light high tech 20 gallon, but have since stopped dosing K2SO4 because I have decreased the fish load such that almost all my nitrates are coming from KNO3. In my low tech 125 gallon, I only does K2SO4, as the fish produce more nitrates and phosphates than is needed already.

As far as I know, excessive K doesn't affect anything, so the bottom line is whether you dose or not doesn't really matter much if you are dosing lots of dry fert nitrates and phosphates.

Have you measured your tank's parameters? If not, it might have to have some baseline readings to work from.
 

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Discussion Starter · #5 ·
Thats another issue i am having.

K - there is no cheap test kit but since extra K doesnt hurt then more is better than lack ?

P - i have read that the phosphate tests are not very accurate. If so how can you get a good gauge on whether or not P needs to be dosed ?

N - also have read that nitrate test kits are not very accurate. If so how can i know if i should be dosing nitrogen ? The way i was planning on doing it was to measure my nitrate levels. If they were above 10 ppm then i wasnt going to dose any KNO3. Is that a good plan ?

I guess what i need to know is once i can get some baseline numbers then i can create a sort of "specialized for my tank" EI dosing regime. But with unreliable test kits how can i get that baseline ?

James
 

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Woah, woah, woah. wait just a dog-gone minute! :tongue:

The whole point of EI is that it's a simple dosing method that doesn't require you to test for all the nutrients!

Tom Barr said:
EI is “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.”
You're trying too hard! Is there a reason you're concerned about the deficiencies? Are you not seeing proper plant growth? How long have you had this tank up and running?

IMO, you should start off dosing KNO3 and KH2PO4 and if you're not seeing the growth you'd like, look into changing it at that time.

With little luck, Tom will add his thoughts....
 

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To check your test kit, just make up a base solution with a known concentration for both nitrate and phosphate, and test against that. That's simple enough to do. But as Solstice said, I don't put much stock in the results, and trust EI more. As long as the plant growth is good, I don't worry about it much. It's the low tech, non EI tank that I test.
 

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Discussion Starter · #10 ·
The thing that bugs me about EI is this (keep in mind im new so i dont know much haha).

For example sake....if i dose say 2 parts KNO3 throughout a week. Then do 50 % water change and add 2 parts the next week again. I could hypothetically have 3 parts NO3 in the tank if the plants didnt use any up. Then the next week do 50 % WC and i could have 3.5 parts NO3 in the tank. Then the next week i could have 3.75 parts etc etc etc....

In the tom barr report he says you cant get more than twice what you are dosing built up in your tank but thats just not true by my figuring....

Eventually over time if you are dosing even slightly more of any nutrient than the plants are using up then you will eventually have sky high concentrations of this parameter in your tank ! So if you arent EVER testing then this IS NOT a far fetched situation and that could cause hell in the tank !

Where is my thinking wrong ?

James
 

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It's not meant to be complex, but many folks always without fail try to make it that way. So I offer explanations, both the simple version and the more in depth version.

If all you want to know is how, state your goal, tank size etc, then folks can help you.

Some folks have high NO3 in their tap, they use K2SO4 in place of KNO3.
Otherwise you do not need K2SO4, however adding it will not hurt........

Regards,
Tom Barr
 

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Discussion Starter · #12 ·
Nevermind my last post. If you take my example and keep on doing the divide by 2 and add 2 thing you actually DO NOT ever get more than double what you are putting into the tank on any given week. The math function approaches double your dose concentration but never passes double. Really cool !

James
 

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Nevermind my last post. If you take my example and keep on doing the divide by 2 and add 2 thing you actually DO NOT ever get more than double what you are putting into the tank on any given week. The math function approaches double your dose concentration but never passes double. Really cool !

James
Glad Your sorted that out. I was going to suggest that You continue the math....:hihi:

Its Your Responsibility to find the "Balance" in Your tank--Lights, C02 and Ferts. Within flexible guidelines---EI simplifies that for You. However, over time, as You learn more and gain more actual experience, You should be able to determine whether you need slightly more or less of something. Until then, I would recommend that You just followe the Sticky by Wolfenxx on the "Water Parameters" forum.

HTH
 

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The thing that bugs me about EI is this (keep in mind im new so i dont know much haha).

For example sake....if i dose say 2 parts KNO3 throughout a week. Then do 50 % water change and add 2 parts the next week again. I could hypothetically have 3 parts NO3 in the tank if the plants didnt use any up. Then the next week do 50 % WC and i could have 3.5 parts NO3 in the tank. Then the next week i could have 3.75 parts etc etc etc....

In the tom barr report he says you cant get more than twice what you are dosing built up in your tank but thats just not true by my figuring....

Eventually over time if you are dosing even slightly more of any nutrient than the plants are using up then you will eventually have sky high concentrations of this parameter in your tank ! So if you arent EVER testing then this IS NOT a far fetched situation and that could cause hell in the tank !

Where is my thinking wrong ?

James
With that explanation, why don't all fish only aquariums build up their PO4/NO4 indefinitely then?

There's no uptake right and you keep adding a source of NO3....?

Why don;t they keep building up?

Simple.

You are removing a fraction of the build up as well each week, not just 50% of what you have added.

This is explained mathamtically in an "infinite series".

From the APD:
http://fins.actwin.com/aquatic-plants/month.200501/msg00416.html

"If you assume that nothing is consumed, and you dose the same amount each week (X), and you change 50% of the water each week...


Week 1 = X
Week 2 = X + X/2
Week 3 = X + X/2 + X/4
Week 4 = X + x/2 + x/4 + x/8

This is a simple series:


__
\ -n
/__ 2 where n goes from 0 to infinity

It converges at 2. To find the maximum concentration multiply X times 2. So at a large number of weeks then you can safely say that the concentration after 50% water change + X is equal to 2X. Doesn't matter if it's KNO3 or fish poop or some allelopathic substance excreted by plants. If you are doing a 50% water change every 4 weeks but are dosing X each week then at the end of a sufficient number of months the maximum concentration of X is 2(4X) or 8X. You can set up a series for any dosing and dilution scheme. Some of them "converge" or have a maximum value. Some don't.

A 10% water change weekly and dosing X gives:


X
X+.9X
x+.9X+.81X
X+.9X+.81X+ .729X which builds up concentration pretty fast."

As you can see, a 50% weekly water changes converges at 2x the weekly dose.

So adding 20ppm of KNO3 every week means it'll never go beyond 40ppm.
Don't like that wide a range?
Try 75% Weekly water changes
That will narrow it between the weekly dosed and possible build up.

50% is just an example and one that works well.

If you did not do but a 10% weekly water change and added 10ppm NO3, run the 10% build up series above..........

Yes, I am asking to use math to show and prove it to your self:)
While not 2+2 = 4 level, it's still pretty clear.

I think many folks are under this illusion, initially I was as well but knew that it could not be right as fish only tanks without any plants had no build up or uptake of NO3 that got good water changes and high very high bioloads.

There is a % of the remainder of the old water that gets removed each time a a new water change is done.

That's the part that gets removed and why the levels of NO3 etc never build up.

This also assumes no NO3 in the tap.A call to the water dept will quickly let you know, say you have an infant and need to know for health reasons, they will snap to fast.

Regards,
Tom Barr
 
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