outsider:
How is Arduino powered? Have you tried powering it from a battery so it is isolated from mains? Post a detailed digram showing ALL components and how they are connected.
man there is soo much stuff connected. let just say the arduino/esp/phsensor/relays/leds/lcds/ are all powered by a 5v samsung wall charger that i tore open and put inside the project box. the sensor reads fine if there are no other pumps/electronic in the water. its when a pump kicks on the reads go crazy. the closest cheapest band aid i found is to drop a earth ground into the water. connect the arduino and the ph probe to an earth via a 10kohm resistor. all of these sensor tie to the same grounds and vccs except the esp is connected to a buck converter. IF i connected it to a battery an eliminated the mains ac power then yes the problem is 100% resolved. except the fact that i cant / dont want to use a battery. i would like to imagine not using a 120 to 12v transformer connected to a linear regulator just because of how big they are,