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I noticed big difference between the two.When selecting for ex. 18ml of Flourish Phosphorus dosed in a 10 gallon tank(US gal) ,the Fertilator shows me 2.14 ppm of PO4 is being added to the tank ,while Yet another Nutrient Calc only shows me 1.24ppm.Why the big difference?

Taken from ''The Barr Report"

" FYI: APC's Fertilator giving erroneous calculations

Had me scratching my head for a couple days on this one but I figured it out.

When you enter your aquarium volume in gallons, the calculation uses liters instead giving a result that is off by the 3.79 liters to gallons conversion factor. When you enter your aquarium volume using Liters, the calculation is still off by 3.79x.

To get the correct calculations for now, till they fix it, select gallons as the unit, but enter the tank volume in liters instead.

I have posted about this error in the Fertilator feedback thread. "
 

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Carpe Diem
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Bummer. I used both ~a year ago to cross check and numbers were very close. TY for the heads up.

(Darn programmers :)).

v3
 

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Discussion Starter · #3 ·
Hey ,OVT! It's actually one of your threads that lead me to The Fertilator ,the thread about your riparium.Stunning plants and flowers!
The quote I took from The Barr Report is from 2010 ,maybe they fixed it ,somewhat,by now ,but ,even after following the : "select gallons as the unit, but enter the tank volume in liters instead." ,still gave me different results.
Maybe the "yet another Nutrient calc" is more reliable? I don't have much experience with online calculators ,but this is the one I come across most often.
 

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Plant Whisperer
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wet programmed both of the calculator programs. Perhaps he used different concentrations for that particular product in the coding? I've found other values match up well. Might just be a one off thing.
 

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Carpe Diem
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I just finished taxes, so, might as well run the numbers through both calcs again over the weekend. It can't be worse then Schedule A? :-!

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The YANC calculator is now fixed. There was a typo for the P2O5 percentage. It was set for 2% but it's actually 3%. I'm not sure about the fertilator accuracy but the YANC is as accurate as possible now.
 

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A whiteboard/marker and a hand held calculator will always be more accurate than programmers. lol Plus everyone likes to round to a different value or not round etc... if you do your own math and stoichiometry you will always have the most accurate levels. There is an awesome guy on YT that will show you how. Plus it makes the hobby more fun and interesting.
 

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A whiteboard/marker and a hand held calculator will always be more accurate than programmers. lol Plus everyone likes to round to a different value or not round etc... if you do your own math and stoichiometry you will always have the most accurate levels. There is an awesome guy on YT that will show you how. Plus it makes the hobby more fun and interesting.
+1, I still do it this way.
Use it or lose it.:icon_eek:
 

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Discussion Starter · #9 · (Edited)
+1, I still do it this way.
Use it or lose it.:icon_eek:
Hi ,Tom,
Could you please give me a link to the ecuation that must be used?
I'm having a tough time finding out ,for ex. ,how many ppm of Fe I am adding ,per ml dosed ,from a solution containing 0.306% Fe ,in 25L water column.
I am not asking to calculate it for me ,I just want to know how it should be done so that I learn to calculate on my own.Thanks.

As I understand it ,0.306%=3060ppm (but-per ml or per 100ml?)
I then divide the 3060 by 25000(volume of water in ml) ,equals 0.1224 ppm - total,for eacch ml added?
 

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To be truly accurate you also need the weight of the solution. Guaranteed analysis are reported as percentages by weight NOT volume. However, since the doses we use are quite small the margin for error is acceptable.

Here's the formula,

Desired Concentration (as ppm) / % of element in fertilizer * 10

So if you want to raise Fe 0.5ppm in 25 liters of water...

0.5 ppm / 0.306% * 10 = 0.1634 ml/Liter

25liters * 0.1634 = 4.085ml

Be careful using this to calculate phosphate and potassium. Laws require manufacturers to report P and K percentages as if they were P2O5 and K2O even though they are not.

For potassium divide the percentage (usually shown as "Soluble Potash (K2O)" ) by 1.2 to give you the percentage of potassium.

For phosphorus divide the percentage (usually shown as "Total Phosphate (P2O5)") by 2.3 to give you the percentage of P. If you want PO4, which for our purposes we usually do, multiply the P percentage by 3.07.

Remember, the analysis is listed as percentage of elements by weight. So for example, don't confuse total nitrogen and Nitrate (NO3).

The molar mass of NO3 is 62.00501 as opposed to Nitrogen which is 14.00672 which means nitrogen is lighter. To convert Nitrogen to Nitrate multiply Nitrogen by 4.43.

The above formula also works for dry fertilizers. To get the percentages use a molar mass calculator (or do the math yourself if you wish lol).
 

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Discussion Starter · #11 ·
To be truly accurate you also need the weight of the solution. Guaranteed analysis are reported as percentages by weight NOT volume. However, since the doses we use are quite small the margin for error is acceptable.

Here's the formula,

Desired Concentration (as ppm) / % of element in fertilizer * 10

So if you want to raise Fe 0.5ppm in 25 liters of water...

0.5 ppm / 0.306% * 10 = 0.1634 ml/Liter

25liters * 0.1634 = 4.085ml

Be careful using this to calculate phosphate and potassium. Laws require manufacturers to report P and K percentages as if they were P2O5 and K2O even though they are not.

For potassium divide the percentage (usually shown as "Soluble Potash (K2O)" ) by 1.2 to give you the percentage of potassium.

For phosphorus divide the percentage (usually shown as "Total Phosphate (P2O5)") by 2.3 to give you the percentage of P. If you want PO4, which for our purposes we usually do, multiply the P percentage by 3.07.

Remember, the analysis is listed as percentage of elements by weight. So for example, don't confuse total nitrogen and Nitrate (NO3).

The molar mass of NO3 is 62.00501 as opposed to Nitrogen which is 14.00672 which means nitrogen is lighter. To convert Nitrogen to Nitrate multiply Nitrogen by 4.43.

The above formula also works for dry fertilizers. To get the percentages use a molar mass calculator (or do the math yourself if you wish lol).
Thank you very much! Now I can practice calculating imaginary solutions till I get the hang of it!
"Lackeys ,bring me pen and paper at once!" lol
 

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Here are a couple of articles about this if you get curious. They are about terrestrial fertilizing methods but the math and methods still apply. The second link talks about why the method I suggested won't be entirely accurate. Although, you can get the density. It's listed on the front of the bottle.

Example Flourish Iron

Net 500 mL(16.9 fl oz)
Net Wt. 525 g(1.1 lbs.)

The Basics of Fertilizer Calculations for Greenhouse Crops

How to Convert Liquid Fertilizer into Dry Fertilizer in Fertigation for Commercial Vegetable and Fruit Crop Production

Liquid fertilizer active ingredients are expressed on a volumetric basis. The density of the liquid fertilizer is a key detail because it is impossible to know the weight of a liquid fertilizer before the density is known. Typically, the net volume and net weight are available on the liquid fertilizer label (Figure 3). The liquid density can be calculated based on these values. For example, on the Dr. Earth® label (Figure 3), its net volume is 0.946 liters (1 U.S. quart), and its net weight is 1.2 kilograms (2.64 pounds). Therefore, its density is 1.26 kilograms per liter or 10.51 pounds per gallon (2.64 pounds/U.S. quart x 1 gallon/4 quarts/gallon). This source is a 3-3-3 liquid fertilizer. A quart of this liquid fertilizer contains 0.08 pounds (36 grams) each of N, P2O5, and K2O (0.24 pounds or 108 grams of N, P2O5, and K2O in total) and 2.4 pounds (1089 grams) of water or other inactive ingredients.
 

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Discussion Starter · #13 ·
Here are a couple of articles about this if you get curious. They are about terrestrial fertilizing methods but the math and methods still apply. The second link talks about why the method I suggested won't be entirely accurate. Although, you can get the density. It's listed on the front of the bottle.

Example Flourish Iron

Net 500 mL(16.9 fl oz)
Net Wt. 525 g(1.1 lbs.)

The Basics of Fertilizer Calculations for Greenhouse Crops

How to Convert Liquid Fertilizer into Dry Fertilizer in Fertigation for Commercial Vegetable and Fruit Crop Production
Thanks!!Although I am not able to completely understand everything yet ,I realised I actually like to spend more time reading ,than looking at my tank.The fun never ends in this hobby!

PS: I tried the ecuation ,with the same numbers ,and :

0.5 ppm / 0.306% * 10 = 16.34
Do I have to divide this result to 100 (because it's per cent?),so I get = 0.1634 ,as you got?
 

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Thanks!!Although I am not able to completely understand everything yet ,I realised I actually like to spend more time reading ,than looking at my tank.The fun never ends in this hobby!

PS: I tried the ecuation ,with the same numbers ,and :

0.5 ppm / 0.306% * 10 = 16.34
Do I have to divide this result to 100 (because it's per cent?),so I get = 0.1634 ,as you got?
Sorry. Do the multiplication in parentheses first. Then divide. As you can see you just move the decimal place to the left one. I only added that because it’s a constant. Ounces per U.S. gallon would be 75 and pounds per U.S. gallon 1200.

0.5 / (0.306 * 10) =
0.5 / 3.06 = 0.1634

Then multiply times your volume in liters...
25 liters * 0.1634 = 4.085
 
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