I have been reading an article by Dr. Daniel Fernandez, on controlling pH levels. He claims using ion exchange resin in a inline filter, where the filter is filled with 1 gram of Amberlite CG-50 ion exchange resin per 1 gallon of solution. The article he wrote is named How to have a constant pH in Hydroponics-No more Corrections. I am hoping someone on the forum knows about this process. Thanks in advance.
Look for Torus Perfect PH, it is a drop in cartridge that keeps PH stable, I have one and it works.