I use the hanna (tds/ec/ph/temp) meter and it works fine for 10 years now...I had to replace eletrode once at 8 yrs of daily use...
i have a hanna tds/ec/ph/temp also, it has cal check on it, I love it! very fast reading, altho i've only been using this one for about half a yr. Before i was using the one with only tds/ec/ph on it and it works just as good just without the Temp.