I want to just thank all of you, and the person who recommended going to Leslie Pools for water testing. I am in Northern Virginia and had a 6000 gallon fiberglass pool installed last year. The pool company that did install is local and has the worst customer service imaginable for $50,000. They caused many problems. Three weeks ago, my water suddenly became cloudy and green after rain. Testing showed very very low PH and Alkalinity. After repeated trips to these local losers, who by the way never tested for water hardness or metal, they told me to find another pool company to work with. Yes, I was angry they would not and could not fix the water problem, Leslie Pool tested for these two and found the calcium hardness was 100, should be about 350 for this pool. It cleared up overnight. Yes, low levels of ph, alkanity and hardness can cause greenness.
I also found that low PH and Alkalinity can cause acidic water which is bad for your pool and equipment.
If anyone in Northern Virginia is thinking of having a pool installed, contact me and I WILL tell you the name of this company to avoid.