i would give more specs on the sensors but there are none. all i know is i need to isolate the ground of the ph probe somehow. my pumps are plugged into the wall outlet. the arduino and every sensor is powered by a 5v usb charger. surly there's some way to isolate the "phsensor" circuit from the mains power supply. where can i ask this question at is there a recommended website that can tell me how to totally isolate the arduino from the mains power and ground? i obviously cannot just isolate the signal from the sensor at the arduino because current can still flow from the water up the sensor cable and out of the sensors cable into the sensors module and out to the mains ground. the waters current leakage is not flowing through the arduino its flowing through the ph sen and its module and to the 5v usb chargers ground. does this make sense? ive spent the last 3 hours explaining the same question