After seemingly ineffectively ammending the soil of my blueberries & rhodies (acidifying), and hydrangeas (alkalininzing), I finally tested my rapitest probe pH meter by probing some tomato sauce: pH 7. So I tried vinegar: ph 7. OK, so it doesn't work---maybe it never did. I see from other posts that the probe needs periodic cleaning---but how? without damaging it, of course. Fixing this problem would certainly be cost effective!

I read many assorted posts on pH meters, but they are all very pricey. Can anyone recommend an accurate one under $50? Or am I asking too much?

Thanks,

Ann