help me to understand EI

hani

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Hi, i have been using the EI for my tank, but i have a question:
lets say we have 29 g tank and we are dosing NO3 three times a week, that will add about 30ppm (11.25 per dose) but lets say its about 10ppm per does. lets assume the plants will use 50%-75% of that. lets say it will use 50% to make it easy, at the end of the week will have 15ppm. if we do 50% water change that will leave us with 7.5ppm. Then we going to start dosing again that will add an extra 30ppm will make the total 37.5ppm. the plants will use half that will leave us with 18.75. will do 50% water change the total will be 9.375.
over few weeks the Nitrate level wil be quite high.
my understanding that the EI tries to over dose , then 50% water change wil reset the tank.
what is am missing?
hani
 

Tom Barr

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See infinite series. Good old math.

If what you are thinking is true, what do you think would happen to every fish only tank which has no uptake of NO3?

The partial water changes would still never stop the infinite build up would they?
This common sense example helps folks to realize that the build is not infinite.


A fraction of the remaining water is diluted each time you do the water change.
It's not additive. that's why in the EI full article you see the graphs" curves leveling off after a few weeks, about 5-10 or so.

See here near the end and here:

Practical PMDD Information

Re: [APD] dilution

Series (mathematics - Wikipedia, the free encyclopedia)

The notion of infinite series and the application to planted tanks is hardly my idea, I just used it to make a point as to common sense..........

I just use common sense to apply what's known to make different more effective methods. I do not really invent anything. Nor do I suggest I do.
However, applying what is known to solve an issue or make an improvement is still a creative art/method.

Regards,
Tom Barr
 

Carissa

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You can never end up with as much as double your total dosing per week (with no uptake by the plants). So lets say you dose 20ppm per week in a tank with no plants. You will never get up to 40ppm no matter how long you do it, as long as you do the 50% water changes.
 

hani

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another question, if the avreage intake for kno3 2ppm/day then the total will be 14 week, why do we dose 3 times a week? what happen if we dose 30ppm once a week only?
thanks
 

Tom Barr

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Wider variations in concentration cause plants to change their uptake enzymes.........so they are best off with somewhat stable conditions, not feast or famine.

There's some play here, but 3x a week is a minimum for most CO2 enriched higher light systems.

At lower light, 2x a week, etc works fine.
Non CO2, 1-2 weeks per dose etc.......

You can dose daily also.
Say 2ppm NO3 per week.
a few tanks may need more, but that's about an average.

Note, that may include some denitrification, not just plant uptake and not all uptake translates into growth directly.

Regards,
Tom barr

Regards,
Tom Barr
 

hani

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thanks for answering, am dosing 3 times/wk, when i test after the first does ,the kno3 is about 12 ( .25 tsp) (29G with 4w/G co2) at the end of the week its about 40. will that be too much variation? should i half the dose?
sorry aking to many question am trying to learn?.
hani
 

VaughnH

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When you first set up the aquarium the plant load is relatively small, compared to what it is after the plants grow for a week or two. So, the demand for fertilizers isn't a constant, it grows as the plants grow, drops as you prune.