Re: [APD] Flourish iron & KH drop

[Greg Morin <greg at seachem_com>]

>
>>  It's not organic acids.  As I said in the original post, I added
>  > 5ml of Flourish iron to 2L of tapwater & in 30 minutes the KH 
>>  dropped from 10 degrees to 7.5 degrees.  Nothing else added!
>>
>>  Anyway, I know the rate at which the KH drops in my 50g - I've been 
>>  running it (& monitoring it) continuously since 1997.  It's 
>>  definitely the Flourish iron which I've just started using.<snip>
>
>
>So how much are you using?
>
>Seachem recommend dosing at 0.5 to 1 ml per 40 litres as required in 
>order to maintain iron levels at 0.1 mg/l.
>
>You've got a 50 gallon = 200 litre tank. Are you dosing 500 ml of 
>Flourish Iron in your tank each time, because that's the equivalent 
>to what you're adding to your 2 l sample.
>
>Your test uses an absolutely massive dose and the EDTA in the product 
>may well be doing something with the carbonates in the water when 
>added at those concentrations. The question isn't what the product 
>does at those concentrations. It's what does it do at the 
>concentrations you dose your tank at.
>
>You've got a 50 gallon tank. That's 200 litres. You're using a 2 
>litre sample. Divide the normal dose you give your tank by 100, add 
>that to a 2 L sample of water, and see what that does. If that causes 
>the KH to drop, then maybe your test is giving you the answer to why 
>your KH is dropping, but if a test using the same concentration of 
>Flourish Iron in a 2 l sample that you actually dose your tank with 
>doesn't cause the KH to drop then you probably need to look elsewhere
>for your answer.
>

I was all set to respond and then I saw this post 
from David Aiken which succinctly makes the point 
I would have otherwise made. Flourish Iron does 
have an acidic pH as formulated (for product 
stability) however it is weakly buffered enough 
that it should not have a significant impact when 
used as directed... which begs the question of 
what your current dosing regimen is, i.e. how 
much in what volume and how often?

What I would add here is that the acidity level 
employed in the product, (when used as directed-1 
mL in 40 L) would only consume 0.004 meq/L (or 
0.012 dKH or 0.22 ppm) of carbonate alkalinity at 
a theoretical maximum, in practice it should be 
well below  even that small amount. To get the KH 
drop of 160 to 50 ppm you saw would imply a 500 
times overdose over the recommended usage.

Also, as an aside... Flourish Iron does not employ EDTA.
-- 
Gregory Morin, Ph.D.  ~~~~~~~Chairman/CEO~~~~~~~~~~~~~~
Seachem Laboratories, Inc.      www.seachem.com     888-SEACHEM
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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