the sunleaves pen is a bit more in price but will read over 2000ppm's. It shows a X when you get over a 1000ppm's. Like 120 times 10= 1200. milwaukee ph pen is great to keep ph spot on , just remember to get calibration and or the storeage solution especially. To store the pen electrod in for longer life of pen. Some times you have to calibrate them both or check at least to make sure your right on.