okay for a week now i have been getting upset about my ph droping, i even got on the emergency post...and i found problem. it was the ph monitor. this stupid one came with cal fluid that you put it in and hit the cal button, if it comes up green its good to go......NOT TRUE....cuz i did that when my ph droped...did it twice....so for a week i have been freakin out.. so i took out my old salifert ph test kit and it tested fine...and i thought no way....so i did the cal test again...and it came up green...so i used a different test kit and it tested good again...so now im just in ohhh.... so i tested the probe in a 7.0 sample and it was way off...same with the 4.0 sample....so i adj..ed both over and over again and now my tank is reading fine.....matt told me that he got rid of his and i might do the same..or i might buy a pinpoint one...dont know...just wanted to put this up so you all will check the cal on your monitors, and not the eazy way..do both the high side and low if yours has it...im not wanting to bash hardware just wanted to remind yall do you mantenence talk to yall later...rich