I've been running a 1-4x40 for 3 years with nearly the same set up. My first recommendation is to go with 2-4x40s at a minimum. You might even want to look at a commercial unit. 1 is too slow for my 175 taps, so I can't imagine how it would be with 500 (unless you really enjoy boiling). Second, get the biggest Procon (Series 5 330gph or Series 6, or some other brand such as Guold) so you have the pressure (Procons look to be limited to 250psi) to concentrate to a higher level per pass. You may even need a booster pump with 2 or more membranes. I'm currently in the process of adding a second 4x40 membrane (Dow Filmtec XLE), a booster pump, low-pressure shut off, flow meters, decent needle valve, and electronic pump start/stop switch (in sequence - booster than Procon 265 on start-up).
This season, for what is was, I would run the RO for many hours to concentrate to somewhere near 8% a 275 gal IBC tote full of 1.2-1.4% sap. Sometimes it wouldn't even get close to that when I wanted to start boiling (so I wouldn't be up all night). Also, Procons are very sensitive. You can't let it run dry for even a minute, or allow your intake to suck air, else pump failure may be in your very near future (voice of experience here, but the pumps can be rebuilt).
It seems to me, excess RO capacity is way better than not enough, so don't cut it short to save a few bucks. Or you can be like me and pay more for it later.
EDIT: BTW, Wateranywhere and Freshwatersystems are good sources for components.
Last edited by Ghs57; 04-11-2021 at 07:52 PM.
Reason: Added detail
Gary / Zena Crossroads / 42˚ 00' 24" N / Hobby in Early '70s, Addiction since 2014
175+ taps on 3/16 (60 of which are on two Lunchbox Vac/Releasers)
12x34 timber framed sap house w/attached 10x34 shed roof for storage
2 x 6 Smoky Lake hybrid pan on Corsair arch with AUF/steam hood/preheater/concentric exhaust
7.0 KW Sun Power PV System, Smokey Lake Filter Press/Steam Bottler, Modified NGMP RO - 2 4x40 posts 200 gph