Quote Originally Posted by rfeiller
If you use an electric pH meter you have to calibrate it frequently with solutions of 4,0 & 7.0. Don't use litmass paper it is easily fouled with humidity. The ppm is used exclusively in hydroponics to measure nutrient levels. Primarily ppm of. Nutrients/minerals. And also used to measurer hardness of water. The ppm can then be converted to the German scale of DH. The try meter you have (I have one also) was compiled to measure the hydroponics parameters. With all of the suspended organics from aquaponics I do not use it as a system monitor for AP.
Yes, I have calibrated it many times. Also you should only use PH Calibration solution of 4 if you are expecting PH results lower than 7. For AP I think I'm going to use the PH 10 Calibration solution as it's pretty rare to have a PH of less than 7 in AP no?