Need to raise 100ppm mag ?

[timi hendrix]

I am using Randys recipe 1 which is 5 cups of Mag flake and 3 cups of Epsom salts into one gallon of R.O. What I want to do is raise my Mag from 1200 to around 1300. How much would I need to get it to that level. FWIW. My Cal is 370 and Alk is 8.:beer:

[bertoni]

If you can get a good estimate of the total volume of water in the system, this calculator should help:

http://reef.diesyst.com/chemcalc/chemcalc.html

I'd target 40 ppm or so for the first dose, since volume estimates can be difficult.

[Randy Holmes-Farley]

This calculator shows how much is needed:

http://reef.diesyst.com/chemcalc/chem_calc3.html

[timi hendrix]

I was wondering how much ppm is in 1 cup? Using that recipe.

[Randy Holmes-Farley]

ppm is a concentration (parts per million, or ~ mg/L), so the recipe is about 47,000 ppm magnesium, whether it is in a cup or a gallon or any other volume. :)