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Originally Posted by Aviel Livay
Tom,
Here's what bothers me with this method, hope you can help me.
In the first paragraph I am required to decide what's the plant maximal uptake rate.
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That assumption is based on the max rates..........we dose above the needs of the plants in all cases anyway.
So this level will provide enough nutriwents for any tank, regardless of light and low fish loads.........
It assumes that deficencies, not excess causes algae.
And you can prove this to yourself with most any nutrient.
So if you have excess, that's not an issue, a very high excess is merely wasteful, but does little if any harm and does not encourage algae.
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Well I think in my tank it's 1 ppm no3 per day - that's because something is wrong, trust me I have enough light, CO2, po4, micros, younameit and this is the maximal uptake with an average of maybe 0.5 ppm no3 per day.
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Sure, that's fine.
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Now if I decide that this is my uptake rate then I start dosing 1 ppm per day. If I keep on doing this and my tank improves for some unknown reason (and there are *always* unknowns) then mid week I shall have 0 no3 and by thursday WC I shall already be infested with BGA.
If I decide that 3 ppm is more likely a maximal rate although my tank eats only 0.5 ppm per day. Then after 7 days I shall have 7 * (3-0.5) = 17.5 ppm. After WC Is hall have 8.75 ppm. And if I continue this math shows that I shall swing between 17.5 ppm after WC and 35 ppm just before next WC. So it this how I am supposed to grow my sensitive plants? For example doesn't Rotala Macrandra prefer low no3?
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No, my client's tank gets high NO3 and has all these plants as I do at home, plants look and grow well, I doubt you'll get 35ppm in your tank, 20ppm is about what many end up with.
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And if I set the uptake to 4-5 ppm then I shall have swings of 30-60 ppm. I tried it - @ 50 ppm no3 the k levels were ~40 ppm (I measured) and ludwigia sp. pantanal leaves curled drastically because apparently K won Ca.
I am not trying to criticize - on the contrary - I just want to better understand.
Thank you,
Aviel.
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I doubt you have 4-5ppm of uptake per day, I'm not quite sure waht your question is here.
I did 75ppm NO3 with KNO3 dosing, I had N pedicillata, I had Ammannia, as have many others, no issues.
We grow L panatal here, many folks do, it's available at the LFS here in Albany, no one has mentioned issues with it and K/Ca.
But we are not adding 50ppm.
I do not suggest adding that much KNO3 either.
See 5-20ppm or so ranges, 20-30ppm should not cause an issue for any plant.
I have soft weater and used soft water the last 3 times I investigated K/Ca issues, it's something else.
I've yet to see this occur in any plant species named. I add plenty of K+.
It might be mulitple things occuring, but it's not K+.
I use SeaChem EQ and add a fair amount, KNO3, KH2PO4........you get the picture.
Plenty of K+. No issues, soft water. Supposed plants that are susceptible....
I don't have a problem and I've not been able to find one...........so I also have little motivation to investigate something I cannot see..........
It's like the old issue with PO4 causing algae, how come I don't have that problem if this is true?
Is there some sort of need to add 50ppm of KNO3?
Take weekly measurements and substract the amount dosed from the water measurement. There is some due to denitrification. You can measure that amount due to denitrification by removing the plants for a week and then adding them back again after the test.
If you are micro managing and taking daily measurements, then the accuracy is not going to be as good, also do this many times, not just one of two weeks. Then try it with many plant species..........
Regards,
Tom Barr