Need help with my EI dosing routine - The Planted Tank Forum
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post #1 of 5 (permalink) Old 01-19-2010, 04:07 PM Thread Starter
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Need help with my EI dosing routine


I have a problem related to macro dosing. But first let me tell you something about my tank:
- tank is about 6 month old, it has the following dimensions (cm): 100x40x40
- lights: 4 x 39 w (T5 fluorescent bulbs - Osram 865) about 10h/day;
- CO2 about 2-3 bouble/second;
- pH around 6.8.
- temperature ~25 Celsius degrees.
- fertilization with microelements is assured by JBL fert. system (substrate, daily and weekly liquid ferts);
- list of the plants: micrantemum micranthemoides, anubias nana, limnophila aromatica, HC, blyxa japonica, pogostemon helferi, glossostiga elatinoides, micranthemum umbrosum.

Now, let's get to the problem:

for fertilization with macroelements I'm using an NPK in an estimated Index regime.
The solution has the following characteristics: for each mll I add in my water I increase the concentration of macroelements with: 1ppm NO3, 0.1 ppm PO4 and 1.33 ppm K.
For a few months now, I'm adding weekly 40 mll solution, in my calculations this addition stabilizes concentrations, over time, at these levels:
- 52 ppm NO3 (at a presumed uptake of 28 ppm / week)
- 78-79 ppm K (at an assumed uptake of 28 ppm / week)
- 5,2-5,3 ppm PO4 (at a presumed uptake of 2.8 ppm / week).

THe question(s):
- are this calculations OK? If not, what is the mistake? what would be the correct weekly addition in order to maintain about 30 ppm of K and NO3 whilst PO4 is maintained around 4-5 PPM?
- if my math is not wrong, and the values are correct, altough my fishes and my plants are OK, isn't wise to dim the concentration to about 30 ppm of K and NO3 whilst PO4 is maintained to this value (I have some GSA problems too)?
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post #2 of 5 (permalink) Old 01-19-2010, 06:44 PM
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Most of the plant species you have are very fast growing and Nitrogen demanding species.

I'm not sure where 52ppm of N comes from, that is not what EI is or suggest.
It's not a ratio either.

It's just a concept and some general ranges.
It can and should be modified to target about 10-30ppm of NO3 at any given time, 10-50ppm for K+ or thereabouts, 1-5ppm for PO4, I like it around 2-5ppm, NO3 about 20ppm etc.

If you want more accuracy, you can use liquid solutions and dose daily.
Up to you, whatever gets the ferts into the tank consistently, daily or every 2-3 days is fine.

Dosing nutrients is easy and straight forward.
I would suggest you spend more time modifying and adjusting light(less is better for most hobbyist) and then modifying and adjusting the CO2 carefully and slowly.

Those two will yield much more success, as EI will make the nutrients independent so you can better focus on CO2 once light has been adjusted to a moderately low range.

The other thing is just watch the tank carefully, plants, algae, fish etc.
Provide good current etc.

Those are more general "test" and with experience, you will find that it works and requires little effort, just basic aquarium care.

Tom Barr

Tom Barr
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post #3 of 5 (permalink) Old 01-19-2010, 07:50 PM Thread Starter
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thanks a lot for response.
In my understanding, you've sugested to reduce the light to a level considerated moderate?
The outcome of this action would be: higher concentration of CO2 in the water (due to the smaller amount of light, and hence a smaller rate of growth)?
I'm asking, if you please, to explain to me how to do the math in my case wich is:
Targeted concentration:30 ppm NO3, my liquid fertilizer adds 1ppm of NO3 at every mililiter added, assumed weekly uptake 28 ppm, initial NO3 level about 5 ppm, 50% weekly water change.

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post #4 of 5 (permalink) Old 01-20-2010, 02:08 AM
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Never mind the math, do this:

Test the tank for NO3.
Dose until it hits 20 ppm.
Test daily to see how fast it drops. (This is how fast the plants are using it)

Set yourself up a schedule where you are dosing often enough for the nitrate not to yoyo too much. A slow climb to the end of the week is fine, if you are following EI procedures of a 50% water change weekly.

Similarly, you can test other parameters and follow a similar method: Test frequently until you know how much your plants are using daily or weekly, then set up the dosing for these levels to climb slowly through the week. Water change at the end of the week resets everything.

Once it is figured out you will not need to test anywhere near so often.
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post #5 of 5 (permalink) Old 01-20-2010, 02:23 AM
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Assuming your plants grow, and grow fast, since they are naturally fast growers, you will soon have a lot more plant mass in the tank than you started with. That increases the usage of the nutrients, so the plant uptake you determined by testing will soon be more than that.

Now, you prune the plants so they don't jam the whole tank with plant mass. The uptake drops back, probably below where it started, until the plant recover from the pruning.

I think this is why fertilizing is best done by dosing for maximum needs, accepting that you are accumulating extra fertilizers in the water, but doing a 50% or bigger water change once a week gets rid of that excess. Now, you can stop thinking about dosing, and move to the really hard part - how to get good CO2 concentration and get it all over the tank, even after the plants do a lot of growing. Since you mention CO2 only as a bubbles per second range, I suspect you could spend a lot of time adjusting that to a better value, and modifying the water circulation in the tank to get that CO2 spread out to all plants better.

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