[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Rising iron levels?

>The odd thing that I've noticed is that I used to add 1/8 tsp. Flourish
>daily before, to achieve a reading of .1mg./L on my Hach iron test kit and
>now after adding only .5 ml. of Florapride instead of the recommended amount
>of 10 ml. with my weekly water change I'm getting an increasing iron reading
>after 2 water changes without adding any additional fertilizer! The reading
>has risen from .1mg./L one week ago to .2 mg./L today. Am I getting a false
>reading from the other trace elements or could the Hach test kit not be
>testing the new form of iron from the Florapride accurately?
probably not... the reading is accurate I try to give you an explanation
based on what I know about ligands and general chemistry (too little!).

Iron gluconate is a compound, where the iron is present in its ferrous
state and when introduced in the tank it's easily broken down because of
it's mild chelating capacity. Once broken, the ferrous iron will be oxidate
very soon in a very rich oxygen environment like a planted tank.
The ferric hydroxide will precipitate down to the substrate very soon too
but ... this is a kind of "two ways" process (SORRY for my terrible
english!).. so you will find Fe3+, OH-, and Fe(OH)3 all present in your
water at hte _same_ time.
Assuming that Tetra Florapride contains EDTA (and it should have EDTA in a
quantity slighty bigger that what is needed to chelate its own iron, or
trace metals), probably its already free EDTA moleculas are trapping  your
ferric ions (coming from Flourish, that in other way would not be available
anymore) preventing them from precipitating. So your iron reading is
raising due to the fact that you have the iron from Tetrapride, and that
recovered from Flourish, both still dissolved into your column water.

hope it's understanble despite my terribel english!