I built my pool as an owner/builder with a lot of research and assumptions (hopefully good ones) so if you notice that my setup as I describe it below is not common, now you know why.
As for my question, I want to know when to backwash. I know about the increase of pressure by 10 but my pressure while running the pump for filtration is 0. Yes you read it correctly, it is zero at the filter and has been for the past 2 months (new pool). This is due to my setup. As you can see from my signature I have the Pentair variable speed pump which I run on 1100 rpms all day long. Consumes 110 Watts... virtually nothing. This according to specs should provide up to 40 GPM depending on TDH. Due to low (maybe moderate) TDH, I know I am getting at least 20 GPMs (large pipes, closeness to pool and not too many curves in the pipes) which is more than enough for turning over the 14,000 gals. My filter (Hayward S310T2) is over-sided and is loaded with zeosand which as you know will keep pressure lower than regular sand due to its low density. Additionally, not sure if this is a direct contributor to the filter's pressure (I know it helps the pump work consume less energy), but I have larger pipes, 3 inches comes in (skimmer + drains) and 2 inches for 5 returns. The inlet 3 inch size is there to support running the pump at high speeds (3000+ RPMs) when feeding my water feature (also 3 inch pipe) which is a grotto / slide 7' tall. The pressure at the filter btw will rise up to 20 when I push the pump to feed the waterfall. Anyway, I have a feeling that the pressure will stay at 0 for EVER during filtration.
Also, as I was writing this post, I was wondering if I should compare the pressure while running the pump at higher speeds. But even then, I have a feeling that the pressure may not increase (didn't notice a change yet) as time goes by due to the other variables. So, I can convert the question to, what if the pressure never rises?