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Re: Calculating Fe concentration

Alex R wrote :
"...So if 1 mL TMG has 0.7 mg Fe, I need 11.3/0.7=16.2 mL TMG to
increase the concentration by 0.1 ppm..."
My response:
IMO may not be that simple.
Assume that TMG Fe content is 0.07% which is all the Fe ions bounded by the
chelators HEEDTA and DTPA as stated by TMG composition. (APD archive Tropica
fertilizer by clc-at-hdc.hha.dk CLAUS CHRISTENSEN Date: Wed, 5 Jul 1995)
At any time not all the chelated Fe dosed in the tank would decompose and
release the free Fe++ immediately. It is a slow process depends on the tank
lighting level, bacterial load, etc.
The 0.1ppm target refer to the free Fe++ in the water at any one time.
(reference : Dupla's book The Optimal Aquarium field data sampling). So the
amount of chelated Fe dosage should be higher.
I would think that a correct method will be by actual Fe measurement,
started with a low dosage level (Tropica suggest 1/2 the recommended dosage)
and then slowly up the dosage amount while monitoring the actual Fe++ level.

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