I have read online in the Krib and heard from reliable sources that iron is hard to accurately measure. I have also read and found it to work that when the plants seem a bit "yellow", just add some (Seachem) iron, and perhaps more if they don't green up. Regards a dosing regime, I would follow Rex Grigg's method listed in his
FAQ as it works fine for me. I'm not sure what you mean by ratios. If you add the doses to the
ppm suggested they will get you to where the tank needs to be.
My fish take care of the nitrates (and almost always the phosphates as well from fish food I believe). Be very careful with over dosing phosphates or big time algae issues can erupt as perhaps you already know. Also, I just add the potassium sulphate at water changes along with epsom salts (for my very soft water to raise the
GH) and occasionally iron. Also I dose some micro nutrients. I use plantex csm +B, but one can use flourish as well, though it seems to bring on algae faster. Of late I barely ever fertilize and haven't scraped algae off my tank in months.
The water changes pull out the excess nitrates etc. and allow the ferts to calibrate to an optimal place at least once a week or so, depending on your water change regimen. I think this is a method that Chuck Gadd advocates.
HTH
