Hi all,
I've recently started testing iron in my 75 gal planted tank (4x55 watt
CF 5000K). I've got a medium plant load, I think - 2 large, 4 medium,
5-6 small, swords and anubias and java ferns mostly, and some floating
hornwort that I cut back weekly to just fill in the spaces (fish = 30
neons, 2 discus, and a few bottom-dweller-scum-eating-types). A little
hair algae, not too much though. Twice weekly I use Seachem's flourish
micronutrient supplement.
So, my Iron was undetectabe using the seachem test kit, and I've been
adding their Iron every day now, in addition to the twice weekly
flourish. Immediately after dosing (5 mL) in the morning, Iron levels
are skyhigh (.8 mg/L, or whatever the scale is). 2 hours later, it's
down to normal (~.1mg/L). By the next morning, it's zero/undetectable again.
It's a little early to say how this is affecting the plants, I've only
been doing this for a week, but what I'm wondering is if this is normal
Iron chemistry? it seems to be really volatile. I don't have any
laterite in the tank or anything, just old crappy gravel from long ago.
Could this have something to do with the dechlorinator I use? It says
"detoxifies heavy metals" on it - could my tank be saturated with some
Iron chelator or something?

How crazy are your Iron fluctuations?

Thanks

-Stephane