I have not spent time to learn how to set HydroBuddy up and use it, but my initial impression is that it may be a good tool for adjusting nutrients. It's oriented toward hydroponics, but through the customization windows I believe it could be made to work with aquaponics and bioponics. Here's a link to HydroBuddy.
Daniel Fernandez has made HydroBuddy a fully open source program.
This looks like a very good tool. Looks like it simply converts from concentration to solid and vice versa. With bioponics, such as pee-ponics, you can see how much ammonium will convert to nitrate. I'd explain, but my keyboard is broken.