Where do I get a PH meter?

A little more history.

The pool went green a couple of months ago and I've been fighting it ever since. I've added about 60 lbs of the granular chlorine and about 6 quarts of copper algaecide (%6). Pool went cloudy for about 2 weeks.

Now is clear but I have some algae growing along the walls again. I tried to upload a picture, but couldn't figure it out. The bottom of the pool is now covered with a fine white silt.

Dealer said chlorine level was off the chart. I'll get algaecide and kit ordered tomorrow. Also try to find liquid bleach. Thanks Kevin