Try Adwa ad100, with built in microprocessor. It makes readings in a few seconds, no need to wait long for taking measurements. Quite oversized in comparison with cheap ph-meters. Shows one digit after decimal point, which I found to be more comfortable for work. Really fast and precise device. Proper storage needed, as required with many other serious meters. The sensor must always be moist (some 7.0 solution in the cap). I love it