Have I finally managed to understand ppm and what happens when you dilute?

[The grumpy one]

This chemistry thingy is something I have always had trouble with.
I am more of a mathematician, so you would think it would be easy for me!
Been playing around and I think I have finally cracked it.

So my thinking goes like this:-

• I dose 4ml (0.004L) of TNC complete every day into my 28l low tech planted tank.
• Lets choose Iron as an example.
• TNC complete has 0.08% Iron (Fe) in it.
• 1% is the same as 10,000ppm
• So 0.08% is 800ppm
• To find out how much Iron ppm I would get in my tank the formula would be.
• C1V1=C2 V2 where C1 is the Concentration of TNC complete (ppm), V1 is the Volume added (L), C2 is the Concentration the tank would get to (ppm) and V2 is the Volume of water the tank holds (L).
• Rearrange formula so C2 is the solution would give C2=(C1V1)/ V2
• We get (800*0.004)/28 = 0.114ppm added each day
• So that is 0.114ppm x 7 = 0.8ppm a week added.

Have I finally got it right?
If I have then 4ml of TNC complete a day gives

Product		Element
L	N	P	K	Mg	Fe	Mn	Cu	B	Zn	Mo
	Nitrogen	Phosphorus	Potassium	Magnesium	Iron	Manganese	Copper	Boron	Zinc	Molybdenum
TNC Complete %		1.5	0.2	5	0.8	0.08	0.018	0.002	0.01	0.01	0.001
TNC Complete ppm		15000	2000	50000	8000	800	180	20	100	100	10
TNC Complete daily dose	0.004
TNC Complete ppm for V2 of	28
Diluted TNC Complete ppm daily for V2		2.143	0.286	7.143	1.143	0.114	0.026	0.003	0.014	0.014	0.001
Diluted TNC Complete ppm Weekly for V2		15.00	2.00	50.00	8.00	0.80	0.18	0.02	0.10	0.10	0.01

 

[Ria95]

The logic and maths for the iron calculation looks correct.

EDIT: Remembered this old trick : For liquids , the number in % multiplied by 10 is the result in ppm you get from 1 ml of solution in 1L of water .

 

[dw1305]

Hi all,

• Lets choose Iron as an example.
• TNC complete has 0.08% Iron (Fe) in it.
• 1% is the same as 10,000ppm
• So 0.08% is 800ppm............
  • We get (800*0.004)/28 = 0.114ppm added each day
  • So that is 0.114ppm x 7 = 0.8ppm a week added.

That look right, 0.114 ppm (mg / L) per day and 0.8 ppm per week. If that one is right? Then the same equation should take you to all the other values, which you could check using RotalaButterfly etc.

It is exactly the same calculation, but people may find that using "mg / L" simplifies the calculation. It is the same unit as "ppm", but relates a little more clearly to your tank volume etc. There are 1000 milligrams in a gram (1 x 10^3) and 1000 grams in a litre (1 x 10^3), add the powers together and you get 1 x 10^6 (1,000,000).

cheers Darrel

 

[The grumpy one]

Thanks Darrel

Wow I finally got there. Not bad for a grumpy old git.

😎