I bought these items (below) a year ago and has made caring for my pool so much easier. There are several factors that determine if the pool water will be causing staining or deposits. they are..
These 4 values from measuring/testing are put into one formula, and that formula will say if your pool is out of balance. meaning, it will either stain or have deposits. So, the only way to tell is to test these 4 things, plug it into the formula and see if the result is 'in range'
https://www.amazon.com/Taylor-Complete-Pool-Spa-Test/dp/B0002IXIHM/
https://www.amazon.com/Easy-Pool-Chemistry-Robert-Lowry/dp/1092188150/