The iron-EDTA IS chelated; that's the function of the EDTA.
You might want to check up on the dosing methods described by Tom Barr on
the APD especially with regard to nitrogen. In my experience nitrogen needs
to be supplemented at least once a week to keep the plants growing well. If
I use KNO3, then there is more than enough potassium there for the plants.
Sword plants are also heavy consumers of calcium so you may need to
supplement that too unless you have hard water & exchange 25% every couple
of weeks. Calcium can also disappear into snails & be absorbed by organic
soil especially peat not to mention that it is used up by the plants. I
think calcium needs to be supplemented about every two weeks or so by one
means or another.
Erik, I took a quick look in the Krib where I thought I might find Thomas'
comments. AFAIK, I haven't read a comprehensive summary of his approach on
the APD, although I have a few excerpts that are quite good. IMO, Thomas
has taken nutrient dosing a step beyond the Sears & Conlin PMDD protocol.
Someday he'll get around to rewriting the FAQ for us but in the meantime we
ought to collect some of our favourite postings for the Krib.
Also we've begun to talk more recently on the APD about the ratios of
nutrients (molar ratios) and this is more meaningful & accurate but also
much more difficult for the average user to understand not to mention
newbies. The APD has become a much more technical forum recently; which I
like however its also greatly reduced questions by newbies & casual
growers. What the heck do you call them?
Steve P