# [Wet Thumb Forum]-ATTN: Math wizards!



## Rex Grigg (Jan 22, 2004)

Here is the challenge. On the side of the Plantex tubs it states that 0.5 ounces will give 2.6 ppm of Fe in 100 gallons of water. So can one of you wizards figure out how to make a stock solution of Plantex CSM that will give 0.1 ppm of Fe in a volume of water? You can even pick the volume, but I would like it in something like 10 or 20 gallons.

Thanks.

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## Rex Grigg (Jan 22, 2004)

Here is the challenge. On the side of the Plantex tubs it states that 0.5 ounces will give 2.6 ppm of Fe in 100 gallons of water. So can one of you wizards figure out how to make a stock solution of Plantex CSM that will give 0.1 ppm of Fe in a volume of water? You can even pick the volume, but I would like it in something like 10 or 20 gallons.

Thanks.

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## Rex Grigg (Jan 22, 2004)

In fact here is the total breakdown on the Plantex tub.

0.5 ounces in 100 gallons of water gives:

2.6 ppm Fe
0.75 ppm Mn
0.56 ppm Mg
0.15 ppm Zn
0.038 ppm Cu
0.023 ppm Mo

The Fe dosing would be great. But what would really help and might show me to be a total idiot is how much Plantex CSM can one dose before the Cu levels reach lethal levels. And since I loaned my copper test kit out I can't recall what those levels are but they are around or less than 0.1 ppm.

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## gsmollin (Feb 3, 2003)

14.2 g of Plantex gives 2.6 mg/l X 379 l = .9854 g. So 14.4 g of Plantex yields 1 g of Fe in water. 

You want .1 mg/l X 37.9 l = 3.79 mg of free iron in your 37.9 l of stock solution. You will need 14.4 g Plantex/1 g free Fe X 3.79 mg free FE = 54.6 mg of Plantex to make 10 gallons of the 0.1 ppm stock solution.

When the free Fe reaches 6.8 ppm, the Cu will be at 0.1 ppm.


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## Sir Plants-a-lot (Feb 16, 2003)

Rex, are you looking for a stock solution that adds 0.1ppm Fe for every ml added in 10 gallons or something like that? if so, then try this:

Measure 30g of Plantex (I think you mentioned before that you have a balance that can measure a few grams) and add 500ml water.

A ml of this in 10 gallons will add 0.1ppm iron.

Regards,
Kevin


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## gsmollin (Feb 3, 2003)

OK, I might be understanding what you meant by a "stock" solution. The concentration of Plantex will be 54.6 mg / ml (NOT /10gallons). So to make, say 500 ml, 54.6 mg/ml X 500 ml = 27.3 g of Plantex.


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## Gomer (Feb 2, 2004)

This might have stemmed from an email I had with Rex. I wanted to add 10mL of Plantex to give my 29g tank 0.1ppm Fe.

Here are the "baby steps" to my solution.

0.5 ounces will give 2.6 ppm of Fe in 100 gallons of water.

I want this to pertain to my 29g, so divide 0.5oz by 100 and multiply by 
29

this means that 0.195oz in my 29gal will give me 2.6ppm.

I don't want 2.6ppm, I want 0.1ppm, so I divide the amounts by 26

this means that 0.0075oz will raise my 29g by 0.1ppm FE.

Now, I have a 500mL bottle and want to use 1/50th of it (10mL) per 
dose.
This means that I have to put 50 times the single dose into the bottle

So 0.375oz in a 500mL bottle. Take 10mL and add this to my 29g tank and 
it will raise it 0.1ppm Fe.

to convert to grams, you multiply 0.375 by (28.4g/1oz).

So I need to add 10.65g of Plantex into 500ml. When I add 10mL of this 
solution to my 29g tank, I will raise it by 0.1ppm.


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## Sir Plants-a-lot (Feb 16, 2003)

Chuck Gadd made a great calculator for dosing macros, but I don't know if anybody has posted anything for micros. I'm not Web-savvy enough to make something like Chuck's calculator, but here is a general equation to guide in calculating micro stock solution concentrations. Hope it helps.

A = your target concentration of the element in your tank in ppm(eg "0.1" for iron)
B = the percent composition of the element in your trace mix (eg "7" for iron in Plantex)
C = the mass of trace mix you use, in grams (eg "10.65")
D = the amount of water you use to make your solution (eg "500")
E = the size of your tank, in US gallons (eg "29")

The increase (in ppm) from each ml of this solution added to your tank would be:

(B x C x 2.7)/(D x E)

Or, the number of ml of this solution you need to add to your tank would be:

(A x D x E)/(B x C x 2.7)

Regards,
Kevin


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## gsmollin (Feb 3, 2003)

> quote:
> 
> Originally posted by Gomer:
> This might have stemmed from an email I had with Rex. I wanted to add 10mL of Plantex to give my 29g tank 0.1ppm Fe.
> ...


.5 * 29/100 = .145

Finishing the problem gives 7.9 g of Plantex in 500 ml to make the specified stock solution.


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## m.lemay (Jan 9, 2005)

Ok, I used to have a scale that weighed in grams till the cops took it away.







But thats another story.
Is that .5 ounces in weight=2.6ppm in 100 gals or is it fluid ounces?
If its fluid ounces I can figure out the dosing for my tank pretty easily. If not. How many teaspoons or fraction thereof does .5 weight ounces equal?

75 gal,pressurized CO2 with controller, 3WPG PC lighting,gravel/flourite 50/50 substrate, Filstar XP3, GH=7,KH=5,PH=6.9,NO3=10ppm, PO4=1-2ppm,K=20ppm+/-, FE=.1ppm


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## Rex Grigg (Jan 22, 2004)

Since Plantex CSM is a dry mix I have to assume that they are talking about 0.5 ounces of dry weight. That equals pretty close to 1 tablespoon. There is pretty close to 2 cups of Plantex in 1 lb. 16 tablespoons per pound.

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## m.lemay (Jan 9, 2005)

So that means that 1 tablespoon would bring 100 gals of water to 2.6ppm iron. Thats cool. I can do the math for the rest.

Thanks Rex

75 gal,pressurized CO2 with controller, 3WPG PC lighting,gravel/flourite 50/50 substrate, Filstar XP3, GH=7,KH=5,PH=6.9,NO3=10ppm, PO4=1-2ppm,K=20ppm+/-, FE=.1ppm


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