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Trace dosing

flygja

flygja

Member
Joined
12 Mar 2008
Messages
1,260
Location
Penang, Malaysia
Hey guys, I haven't been able to figure out how trace elements are dosed according to EI. From what I read, it doesn't matter much since the uptake is low, so amounts are measured by the Iron concentration. I bought these trace elements powder - http://www.auasia.com.my/products_cifo_mikrom.htm. The concentrations are listed as:

Boron (B) water soluble 0.5%
Copper (Cu) water soluble, chelated with EDTA 0.5%
Iron (Fe) water soluble, chelated with EDTA 4%
Manganese (Mn) water soluble, chelated with EDTA 4%
Molybdenum (Mo) water soluble 0.2%
Zinc (Zn) water soluble, chelated with EDTA 1%
Magnesium Oxide (MgO), water soluble 3%

Aquaessentials' trace mix plus concentrations are list as:


Boron 1.06%
Copper 0.23%
Iron 8.2%
Manganese 1.82%
Molybdenum 0.15%
Zinc 1.16%

Should I be dosing the Mikrom elements at double the amount compared to trace mix plus since the Iron concentration is only half? I'm a bit concerned since the Mikrom elements has double the Copper concentration.
 
I really wouldn't worry about the copper amount too much. Many people have dosed Garden Direct Chelated Trace Mix, which is 1.7% Cu without any effects. Just dose per standard EI and see if there are any problems. You'll know within a few weeks whether you have an Iron problem. The amounts are really too small to worry about and trace mix cost more than macros so save money and save worry. If you need more then add more.

Cheers,
 
Save on worry, I like that. Thanks ceg!

But seriously though, who measured the amount of traces to dose in the first place? o_O Was it through observation?
 
Yeah, CSM+B was a standard hydroponics trace mix at the time and was a cheap alternative to whatever commercial trace mixes were available. It's content simply became the standard by default, not because it was anything special. Any powdered trace mix you buy is already a hundred times more concentrated than the watered down commercial mixes anyway If you do the actual calculations, you'll see that ppm values are very small.

A typical trace EI dose on a 20G tank is 1/16th teaspoon twice weekly.
Lets say a teaspoon of trace mix weighs 6 grams. That means 6/16 = 0.375 grams per dose. That's equal to 375 mg per dose. That means added to a 20G (80L) tank the total trace concentration added will be 375mg/80l = 4.7 ppm.
But assuming the reported percentages of metals is by weight, then the Cu % of 0.5% means that you have to multiply the total ppm by 0.5% or .005 right? So 4.7ppm*(.005)= 0.02ppm Cu per dose.
With that very same dose, the added Fe concentration will be 20X higher so that equals about 0.4 ppm Fe. Since the weekly dosing of Fe suggested is 0.5ppm this trace mix, if dosed twice weekly, gives you 0.8ppm Fe which is still 60% higher than suggested.

Even if I've miscalculated the volume of water in a typical tank, I'd only be off by about about 20%. Even if my grams per teaspoon estimate are off, I'm still in pretty good shape, both from a nutritional standpoint of Fe and from a toxicity standpoint of Cu. That's how the mixes are designed. You'd have to intentionally dump boatloads of trace mix in the tank to get significant toxic effects, and you'd have to try hard and add practically nothing to the tank to get starvation effects. Isn't EI cool? 8)

Check out JamesC's Trace Mix Comparison for more details on percentages.

Cheers,
 
ceg, that makes it quite clear to me now. Been trying to wrap my head around calculating ppms from percentages and all that. Turns out I just needed you. Thanks again! :thumbup:

The 1 kg bag of Mikrom I bought costs the same as one 500ml bottle of Seachem Trace. And I calculated it would probably last me 25 years on a 20G tank. Score! :lol:
 
Bingo!

Neo to Morpheus: "Why do my eyes hurt?"
Morpheus to Neo: "Because you've never used them before..."

Cheers,
 
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