I wanted to get this out there and see what other people thought about it.

A while back I found myself dosing a lot of iron into my tank (Seachem iron at least 1 capful a day). But I started getting tired of sucking on the iron nipple (i.e. always needing it - and paying for it, $8 for 250ml per month is no fun) I couldn't find any chelated iron where I live so I thought I'd try adding iron pills into my substrate.

I did it and my plants have stayed really green. So it doesn't seem to have had any adverse affect (I added them about 4 months ago). And now I don't need to add much if any iron to the water (and really only for the floating plants).

The iron pills I use are:
Nature Made 65mg Iron tablets from Ferrous Sulfate.
Ingredients> Ferrous Sulfate, Cellulose Gel, Dibasic Calcium Phosphate, Croscarmellose Sodium, Hydroxypropyl Methylcellulose, Titanium Dioxide (artificial color), Magnesium Stearate, Polyethylene Glycol, Triethyl Citrate, Polysorbate 80, Sodium Citrate.

Iron gluconate ought to be available as well, adding Fe to the deeper substrates that have some organic matter will reduce the Fe3+ to Fe2+ naturally via bacteria and low O2.

The chelator is rather weak with gluconate and is often what's used in Vitamins and in the SeaChem Fe. This means it's very easy to break the bond for the plant, but it also means it will not last in the environment long also.

DTPH last longer and is a nice middle ground.
Iron filings, iron "dust", nails etc have been added to substrates in the past and seem to work.

Regards,
Tom Barr

Tom,
You've sparked my curiosity... What's DTPH? And do you mean that I could actually take some iron nail I found at Home Depot and put it in my substrate?

Yes,

DTPH is a type of chelator, like EDTA, but slightly weaker and better optimized for our pH ranges.

see older APD post about Fe and filings etc

Regards,
Tom Barr