Its great I got one for Christmas. Although it is a little time consuming and patientence breaking first calibrating it. It also help tell me that I have a pH problem.
I have one too, and they are great. Yeah, the calibrating thing is a bit of a pain, but when I first got it, I had a PH problem that I didn't know about either. It's amazing how off test kits can be.
Just another vote in favor or it. I like it and always being able to follow the changes in pH through the day with it from morning to night by just looking at the thing is great.
I know you've heard it before, but yeah, they are great. Go to american marineusa.com and they can hook you up. The owner is very helpful, and you will thank yourself later for doing it. Here is a pic of my 3 (PH, Salinity, Temp) a bit fuzzy, I know.