Chelating iron

Hello everybody

I got a couple of people asking about the iron/trace element mixture that 
I make and I thaught that I had better put it up and see what people 
think of it.

As to background, it is a modification of trace element stocks that are 
used in plant tissue culture. Just about every plant that has ever been 
tried will grow on Murashige and Skooge (MS) media. Recently is has been 
used to grow Cryptocoryne's to maintain an endangered species, Annubias 
barteri var have also been grown on this medium. The liquid form will 
also grow Ottelia alismoides in a growth room here.

Ok to the recipe

For 500ml of 10,000 times stock you need

5g FeCl2
0.5g MnSO4.4H20
0.5g ZnSO4.4H20
a trace of Na2MoO4.2H2O
and 7.4g of Na2EDTA (I add it as a .5M stock at pH8) EDTA does not like 
to dissolve in acidic media and that it is why I make a concentrate.
The actual dose rate depends on the iron content of your tank, and should 
always be used in conjunction with an iron test kit. (which incidently is 
only Potassium thiocyanate and sulphuric acid). At 10,000 dilution this 
gives a concentration of .5ppm.

The water here is very soft with a calcium hardness of only 20ppm. 
Nitrates have not been measured, but we are high in the mountains (well 
for Australia anyway) and centered in a large area of National park, so 
my guess is that the levels are pretty low. I make the hardness up in my 
tank with a propriety product that has Ca, Mg, K, Na etc. The fish that I 
keep are almost entirely rainbowfish with a few ancistris and corydoras 
thrown in.

The plants that I keep are a variety of swords (5sp), cryptocorynes (12sp), 
hygro, ambulia, java fern, thai fern (this one I do not know what the 
scientific name is), aponogetons (4sp), and  "ammania". 

An alternative is to get the Iron fertiliser that is at your garden 
centre and correct the amounts for the purity of the chelate. Some of 
these have clay in them as a carrier, just let it sit a day or two and 
you will not have to bother about the clay. I have a friend that is doing 
this and the results are pretty good. Caution does need to be exercised 
with this option because some "trace element" mixtures may have nitrate 
in them etc, so if you do this make sure that it is a straight iron 
chelate and not a trace mixture.

Hope this helps some people