stephane wrote in message ...
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


Similar.
Iron complexes with about 10-20 inorganic chemicals, and more organic
chemicals or precipitates out of solution, determining how much you
need for your plants, the bioavailabilty, test kits are not very
useful.

A better approach is make sure you have good CO2/NO3/K/PO4 and GH
levels.
If these are kept in good shape, then you can add a known amount
Flourish to a known volume of water. Generally, I've found 5mls 3x a
week per 20-30gallon to be sufficent even at high light, depending on
plant biomass in the tank.
You can split this up to daily dosing etc, but this path will build on
itself startying with good CO2 and working your way downward to the
micro nutrients.

I have a 75 gal and use Flourish also, I add 15-20mls every other day
but I have 330w of light. I'd try at least 10mls 3x a week if you have
decent plant biomass.

Keep the NO3/K+/PO4 in good shape, 10ppm/10ppm/.5-1.0ppm and the GH at
5 or higher degrees. CO2 at 20-30ppm while the lights are on. Test the
pH in the am and the pm to make sure/certain there is plenty of CO2 in
there.
You use CO2?

This should clear up a fair amount for you.
The other issue is that recommendations are often for not as densely
planted, CO2 enriched high light tanks. So adding 2-4x the amount is
not uncommon, Claus from Tropica, about adding Tropica Master Grow
said what I added was normal although it's not as rich iron wise as
TMG.

Regards,
Tom Barr