Review on Low Pressure Liquid-Filled Water by Carlos Macy

I have two gauges installed at the entrance to my well - digital and analog. I bought this to use water filters but tested it before plugging the filters in and this shows a low pressure of 7-8psi (more than 10% difference). I can live with that, because I'm actually only interested in whether the pressure drops due to clogged filters - I only have to remember the delta as a guideline. This is annoying, but not an obstacle.