how do i explain nitrate calculations to a non-believer?

[Martin]

right..

how can i explain the calculations behind how many grams to add to achieve x ppm in tank etc?

he refuses to see the logic in it. Chuck's wrong, tom's wrong everyone is wrong...

he keeps insisting that the calculations of grams pr gallon, is off, because they do not take into account that kno3 is only 38% No3..

can someone explain it in nice & cozy words, so i can convince him...

he wants to add 6.4grams of kno3 every other day, to maintain a level of 5 ppm... but according to chuck's calc. if i add 6.4 grams i get 12,07 ppm...

I dont get his thinking...

This is his calc. translated by me..:

if we want 5 ppm in the 325L(85,3g) tank this will be the way to go:

5 * 325(85.3) = 1625 ppm

1625 * 2 = 3250 ppm

3250/ 1000 = 3,2g. that's how much nitrate we must add:

but seeing as kno3 only contains 38 % nitrate

we must add this:

100/38 = 2,6 * 3,2 = 6,4gram is what we should add.....



perhaps im tired/stupid/non-mathematical, but i cannot see his way of thinking....

 

[Tom Barr]

Re: how do i explain nitrate calculations to a non-believer?

right..

how can i explain the calculations behind how many grams to add to achieve x ppm in tank etc?

he refuses to see the logic in it. Chuck's wrong, tom's wrong everyone is wrong...

he keeps insisting that the calculations of grams pr gallon, is off, because they do not take into account that kno3 is only 38% No3..

can someone explain it in nice & cozy words, so i can convince him...

Err why do you have to convince him?
Simply show him a chem 101 book and how to make solutions.
Perhaps he thinks all the reef folks are nuts also?

Add to 1 liter of water, 1 gram of KNO3. There are 62 grams of NO3 per mole of KNO3 (101.1 grams per mole) and 39.1 grams of K+.
So for each gram, there is 62 grams of NO3/101.1 grams of KNO3= 61.3% of the weight will be NO3.

So 0.613 grams in one liter = 613ppm NO3, since mg/l = ppm.

He can convert and scale up to gallons by a factor of 3.785.

He missed something, he needs to figure out what it is, the rest of the wolrd is not wrong, but he is.

So let him figure it out.

1/4 teaspoon added to 20 gallons of tank is about 11-14ppm of NO3.
The weight of a 1/4 teaspoon is about 1.67 grams KNO3.
The liter volume of a 20 gal tank is 20 x 3.785= 75.7 liters.

1.67 grams of KNO3 x .613 NO3 = 1.024 grams of NO3

1.024 grams of NO3 in x 1 liter/75.7 liters = 13.5 mg/l
Or 13.5ppm for each 1/4 teaspoon added to a 20 gallon tank.

I give some error for water in the salts/different gravel volume etc.
But the error is close to 1-2ppm, which is better than a Lamotte test kit can do.

He has conversion problem or missed the liters to gal, or the mg/l to ppm etc, something. He might be using only N instaed of NO3 or has his K and NO3 molar weights mixed up based on the 38% thing you mentioned.

Regards,
Tom Barr



















he wants to add 6.4grams of kno3 every other day, to maintain a level of 5 ppm... but according to chuck's calc. if i add 6.4 grams i get 12,07 ppm...

I dont get his thinking...

This is his calc. translated by me..:

if we want 5 ppm in the 325L(85,3g) tank this will be the way to go:

5 * 325(85.3) = 1625 ppm

1625 * 2 = 3250 ppm

3250/ 1000 = 3,2g. that's how much nitrate we must add:

but seeing as kno3 only contains 38 % nitrate

we must add this:

100/38 = 2,6 * 3,2 = 6,4gram is what we should add.....



perhaps im tired/stupid/non-mathematical, but i cannot see his way of thinking....[/QUOTE]