Hi all,

I was just trying to replicating that 1ml/20L = ppm?? if you understand.

I do, but ADA won't tell you what the fertiliser contains, so it will all be guesswork. My only comment is that this is probably the most expensive water on the planet in those bottles, and that the nutrient addition will be a fraction of EI levels.

Personally I use a different approach, I don't add any nutrients on a regular basis I just use the growth, and leaf colour, of a floating plant to <"

estimate nutrient status">.

Rather than the regular addition of nutrients, I use <"

a different approach">. I have a floating plant (usually <"

*Limnobium laevigatum">*) and ,<"

heavy planting"> of <

"easy" plants"> in the tanks. I just watch the <"

growth and leaf colour of the floating plant"> (so not CO2, or light, limited), all the time the leaves are green and the plant growing (how ever slowly) I don't add any nutrients (other than whatever arrives via water changes).

When plant growth (or leaf colour) deteriorates I add some nutrients, once growth has resumed it is back to observing and waiting.

If you want to work out the addition of nutrients from the compounds, that you already have, it is quite straight forward.

I'll use KNO3, so that dissolves as a K+ and a NO3- ion. The RAM of potassium is 39, nitrogen 14 and oxygen 16, so the RMM of KNO3 is 39 + 14 = (16 * 3) = 101, so ~40% K and 60% NO3.

When you have one gram of KNO3 you have 0.4g of K and 0.6g of NO3. You can convert grams to milligrams by dividing by 10^-3 and to micro-grams by dividing by 10^-6. So 0.4g of K is 400,000 micrograms. You can convert grams to kilograms by multiplying by 10^3, and one kilogram of water has the volume of 1 litre (1000 cm3).

I'll assume your tank is 100 litres (so that I can do the maths easily), when you add 1g of KNO3 you've added 0.4g of K+ ions, which is equivalent to 400 milligrams and milligrams per litre is equivalent to ppm. Divide 400 by 100 and you get 4ppm.

You have added 4ppm K and 6ppm NO3. If you want to check you can use the calculator at <"

Rotala Butterfly">, which will give you a more accurate, 6.13 ppm NO3 and 3.87 ppm K.

cheers Darrel