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.

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.

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?

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.