Hey folks! So, i don't have a problem, just an interesting observation that i can't explain.
I run my pump 5x 1-hr intervals/day and i have a digital pressure gauge in addition to the standard analog one.
What i've noticed is that there's a fairly consistent baseline pressure variation with a period of about a day. The amplitude of the variation is about 1.5psi, so it's not particularly noticeable on the analog gauge. Also interesting is that the variation is there regardless of whether the pump is on or off -- that is, you can see that the pump is *adding* about 11psi when it's on, but the curve continues fairly smoothly despite the offset.
Screen Shot 2015-12-04 at 12.02.09 AM.jpg
I can understand why the "off" pressure is negative (the water in the filter is suspended about 4ft above the level of the pool by the vacuum), but does anyone have an idea about what would cause the variation? The minimum is around 3-4pm. The pool gets sunlight, but the pump and filter are inside the garage. Maybe i'll start tracking temperature (water, outdoor air, and garage air) to see if that correlates. Maybe i should track barometric pressure as well?
In-ground pool. Cartridge filter. Just one pump. Main drain/skimmer balance comes from a skimmer float valve.
Light gray is the the full range of data, but it's noisy. Dark gray is a 5-min average, which is much smoother.