"Dave M. Picklyk" wrote:

I got an iron test kit today and found out that I do not have any amounts of
traceable iron in my 48 gal. planted tank. I've added some liquid fertilizer
that is iron-enriched. I've tested the water again in a hour and there is
about .35 to .4 mg/L now...which I've heard was good.

Is liquid fertilizer a good way to supplement iron to a system? How long
will it be till I usually have to add more in? (Or I can continue testing
every 3-4 days for chelated iron levels)

Tom described dosing in his reply. As far as a good source, Flourish Iron from
Seachem is extremely convenient, as it is just Iron in liquid form. Also, the
trace mixes used by many here (like Plantex) contain Iron premixed with the rest
of the traces in fixed ratio.