Now I'm a pro and don't need an app and graphs of my params to see things are going well. This is a gadjet.
Juste remember thoses optimal things:
NH3: 0ppm
NO2: 0ppm
NO3: The less possible
PO4: <1ppm
KH: Depends of fishs, 8-10dKH° for reef
GH: depends of fishs
PH: Depends of fishs, 8-8.4 for reefs.
Temp: Depends of fishs, 25-27.5 C° for reefs
Ca: 400ppm for reef
Mg: 1400ppm for reef
Just by knowing this and about the nitrogen cycle, you don't need this app. But if you wants graphs of the params and give name to your fishs, this may be cool