What do the colors mean on the Orenda App LSI Calculator?

The values at the bottom of the Orenda App's LSI Calculator change colors depending on how balanced the water is.

The colors at the bottom of the LSI calculator indicate how balanced your water is on the LSI. Red is aggressive, low-LSI water. You should avoid red at all times. Yellow is acceptable balance, though less than 0.00, which is perfect balance. Green is ideal water balance, and Purple is a high-LSI, scale-forming condition. 

Tap the hyperlinked LSI to see the color legend pop up on the calculator. It looks like this: