FertCalc - Aquarium Fertilizer Solution Calculator Macro Solutions in PPM

This is the only FREE aquarium fertilizer app I know of. Quick "Plug and Play" type application. You need to know a few things like the size of your mixing container and how many mL you want to does and the rest fills in by itself. There is an advanced area two if you know the exact PPM you want of each fertilizer. Great app. Simple and to the point!