FYI, I have developed a dry powdered form of Fe gluconate, same stuff as SeaChem Flourish Fe BTW.
It's just dry(shipping is 10X less) and lot cheaper.

Alan will be selling and I'll have the % Fe for you folks here in a week or so.
I am still planning to get something rather new and 100% absorbable by plants(they cannot use the gluconate nor ETDA, DTPH etc) and have found a highly super rich product that is ideal.
It's about 18% Fe.

The rest is a protein plants can take up diretcly and use as nitrogen source.

Regards,
Tom Barr