Review on CityFarmer Digital pH Meter for Hydroponic Nutrient Solution Testing, with 2 Pack Calibration Solution Mixture, Accurate & Reliable Results, Built-in ATC by Victoria Gomez

This is my second purchase of this product (stepped on the first one, oops). I have tried several other gauges and this is by far the best. Unlike other pH meters, this one uses a screw for calibration. This gives you the most accurate readings over the widest dynamic range. This is not the case with gauges that require the push of a button to calibrate (less accurate, less range). And this comes already calibrated (for pH 7). It would be 5 stars but it doesn't turn off. Replacing batteries costs more than the product itself.