Another iron dosing question - The Planted Tank Forum
Old 04-24-2015, 02:17 PM Thread Starter
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Another iron dosing question

I know I should be able to do this math, but for whatever reason, I just cannot figure out how to do it.

I want to dose EI in my 75 gallon. I am going to dose CSM+B and 10% DTPA Iron.

I found that the ratio is supposed to be 3 parts CSB to 2 parts DTPA.

I want to mix up a solution in a 500ml bottle and dose 20ml every other day.

Can someone help me figure out how much of each of these I need to add to make my solution?

My math came up with 32.6grams of CSM and 14.2 grams of DTPA.

Does this seem correct?
Does this amount of CSM+B give enough of the rest of the micros?

Ben
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Old 04-24-2015, 03:02 PM
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The calculations you made were based on the following:
1) Reach the combined EI goal of .5ppm of Iron
2) Mix 60% of the iron from CSM+B (containing EDTA chelate)
3) Mix 40% of the iron from DTPA iron.

But the end result gives only 60% of the other micros in the CSM+B.

I would now assume that you are supplementing DTPA iron because you don't trust the uptake of the EDTA iron? Or perhaps you want more than .5ppm iron?
If this is true, then you should be dosing CSM+B at 100%, and adding the extra DTPA.

Do you think the 3:2 ratio is because about 40% of the EDTA iron is wasted? Without knowing why you are supplementing DTPA, it is hard to know how much of it to dose...
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Old 04-24-2015, 03:11 PM Thread Starter
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It is based on a post here about needing additional iron than the csm provides at standard ei dosing. The recommendation was for a 3:2 csm:dtpa dosing.
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Old 04-24-2015, 03:58 PM
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It seems like the correct calculations are:

1) csm+b = 54.35g (this will give you the proper 100% of micros, and .5ppm of EDTA iron)
2) DPTA 10% iron = 23.625g (assumes a 3:2 ratio OF IRON, which is .333ppm of DPTA)

This yields a combined iron of .8333ppm.

But since I don't really understand the 3:2 ratio, please wait for someone to confirm this.
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Old 04-24-2015, 04:07 PM Thread Starter
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I will try to find the post and link to it in case it helps.
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Old 04-24-2015, 05:18 PM Thread Starter
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Old 04-24-2015, 05:34 PM
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It is what I expected. The iron products in that post are being adjusted because of higher pH. EDTA does not hold up well in higher pH water.
What is your pH? Do you experience clouding when you dose csm+b?
If you do experience clouding, it suggests the EDTA chelate isn't working, and you need more DPTA, probably in the ratio of 3:2 as expected.
However if your pH is low, and the EDTA is staying chelated, then a 3:2 ratio would only overdose iron.
Thoughts?
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Old 04-24-2015, 06:17 PM
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3:2 ratio is a total of 5 parts

We need the percentage of each part...

3 / 5 = 0.6 (60%)
2 / 5 = 0.4 (40%)

So we need 60% and 40% of something.

In this case it's iron. We want a total of 0.5 ppm of Fe for EI.

60% of 0.5 ppm?

0.5 * 0.6 = 0.3 ppm

So we calculate a Plantex dose of 0.3 ppm

40% of 0.5 ppm?

0.5 * 0.4 = 0.2 ppm

So we calculate the DTPA 10% to 0.2 ppm

Plugging those numbers into a calculator using the solution variables we get

32.6 gm of Plantex CSM+B and 14.2 gm of DTPA Fe (10%)

Make sense?
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Old 04-24-2015, 06:37 PM Thread Starter
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I do have very high pH and very hard water. My pH is around 7.8.

Zorfox, do I need to worry about the rest of the csm traces being to low if I am only using 60% of the recommended dosage?
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Old 04-24-2015, 07:29 PM
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Quote:
Originally Posted by benealing View Post
I do have very high pH and very hard water. My pH is around 7.8.

Zorfox, do I need to worry about the rest of the csm traces being to low if I am only using 60% of the recommended dosage?
I wouldn't think so. However, you can just target Plantex for 0.5 ppm and add another 0.2-0.3 ppm of DTPA if it concerns you. You'd have to dose quite a lot of iron to cause issues. Always err on more when dosing for EI.

Adding the amounts below to 500ml and a 20ml dose will raise iron by 0.7ppm in 75 gallons.

54.3 gm (approximately 12 3/4 teaspoons) of Plantex - 0.5ppm Fe
14.2 gm (approximately 3 1/4 teaspoons) of DTPA 10% - 0.2 ppm Fe
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Old 04-24-2015, 09:17 PM
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What about the 3:2 ratio, which now that the pH is confirmed to be high, would be relevant?
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Old 04-24-2015, 11:43 PM
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Quote:
Originally Posted by imcmaster View Post
What about the 3:2 ratio, which now that the pH is confirmed to be high, would be relevant?
Sorry, I don't understand the question.

Is it a good idea to use DTPA with high PH? Yes.

I think three forms of Fe would be the ideal method, but that's just me. ie. Ferrous gluconate, EDTA and DTPA.
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Old 04-25-2015, 01:06 AM
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Quote:
Originally Posted by Zorfox View Post
Sorry, I don't understand the question.
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