What are you using for a meter, Shov? I broke down a couple weeks ago and got a Hanna HI99104. Not real expensive ($35), but more than double that by the time you get the calibrating & storage solutions.

Was using the dye drops and never felt comfortable with that. So far, this thing seems to work pretty well and I'm adding about the same up/down as I was with the drops. Feel like a damn chemist by the time feeding is over.