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Fe DTPA stock solution help

Mdcabs said:
Jus bought this iron from amazon

http://www.amazon.com/Chelated-Organic-Hydroponic-Aquaponics-Soluble/dp/B00VDHA16W/ref=pd_sim_86_2?ie=UTF8&dpID=31eaSH1KVYL&dpSrc=sims&preST=_AC_UL160_SR160,160_&refRID=0DRS6X2FS6PYYWCTZPM3

It is FeDTPA 10%, i want to know the calcs needed for a 100 ml stock solution. My goal is 0.1 ppm in my tank.
Thanks!
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Hello,
Assuming this is 10% Fe by weight, then 1 gram of powder contains 0.1 gram of Fe.

Fe-ppm = (mg-Fe)/(Kg-TankWater)

Let Kg-TankWater = 50 (i.e. 50L)

0.1ppm = (mg-Fe)/(50Kg)

mg-Fe = (0.1ppm)x(50Kg) ==> 5mg

In order to add 5mg-Fe to the tank, [ 5mg/10% = 50mg ] of powder must be added to the 50L tank because the powder is only 10%Fe.

You did not specify the size or frequency of of the dose. The dosage size and frequency directly determine the amount of powder to add to the 100ml stock. I will assume a 5ml dosage 1x per week.

In a 100ml stock solution there will be 100ml/5ml = 20 doses in the bottle.

In order to deliver 50mg of powder, in a 5ml dose, 20 times, to a 50L tank, then you will need to add (20-doses)x(50mg per dose) = 1000mg of powder to 100ml of water.

If you wish to dose 2x per week to the 50L tank, instead of once per week, the stock solution must be half the strength, so 500mg of powder should be added instead of 1000mg.

If you wish to dose 2x per week and if the tank size is twice as large, then you need to double the stock solution strength and you're back to adding 1000mg to the 100ml solution.

Hope this helps.

Cheers,
 
hello, thank you for your answers!
yeah i missed it, my tank volume is 100L, i assumed that a goal of 0.1 ppm is correct for DTPA iron as i have read in may places that this kind of iron sticks for arround 2 days in tank, should 1 aim for, say, 0.3 ppm? i currently stick with EI dosing methood, unfortunately i dont have acces to micro solutions, just add the macros and iron.
I was thinking in 25 grams in 250 ml, where a ml of this stock solution will raise de iron content of a 100 liters tank by 0.1 ppm or mg/l (the same thing) am i correct?
 
Hello,
You can aim for whatever ppm seems reasonable and then observe the plants to determine whether you need a higher dosage or whether you can get away with less. I try to discourage people from getting too caught up in ppm numbers because it often leads to a mind set which can become counterproductive. The EI dosing scheme, as any other dosing scheme, needs to have some basic numbers, but the numbers are not law. They are more: "these numbers will generally keep you out of trouble from a nutritional standpoint" rather than: "you must achieve these numbers or else". Prior to EI or PMDD, people were terrified of dosing any nutrient, fearing algae and toxicity and they sought to eliminate nutrients from their water at all costs. Other dosing schemes sought to rigidly control numerical values so as not to fall below and not to go above the target number. Again, this rigidity was based on the fear of algal blooms and toxicity. When it was discovered that neither algal blooms nor toxicity were related to increased nutrient loading it was then easy to offer a dosing program that would cover all variations of CO2 injected tanks such as lighting levels, CO2 injection rates and so forth.

So the target level of any nutrient is a soft target and is driven by the other things that you do. The only rigid rule in this scheme is to avoid malnutrition. so if 0.1ppm Fe avoids Fe deficiency then use that. If there are still symptoms of malnutrition then a higher dosage can be used.

25,000mg added to 250ml means that each ml of solution delivers 25,000mg/250ml = 100mgFe per ml
100mg added to 100Kg of water gives you 100mg/100Kg = 1ppm or (1 mg/l) of Fe.

Cheers,
 
Thanks man, this really helped me out. I wanted to know this numbers just to have a starting point of how to dose Fe. i have been using EI first with dry salts, then started making out stock solutions of 30g kno2 and 7.2 g of kh2po4, dosed 5 ml every 50 liters so i dosed 15 ml. I found out that my nitrates and phosphates were balanced but really high so started dosing out the galf i sed to and plants are still growing like crazy.
 
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