EC pen shows 510 ppm. I know that's high, but is it something I should worry about or should I adjust accordingly?
Is that 510 ppm reading straight out of the tap?
I think my well water, even after going though the RO filter is sitting around 8.0 ph. I would say starting ppm is way more important than starting ph. Ideally you want as low ppm for your source water as you can get. Not sure how the science works behind it, but the starting TDS in the water somehow competes with the actual nutrients and causes the plant to not get enough of the nutrients it needs. I ended up having to get an RO filter, without it I would be dead in the water, pun intended
Our water comes out of the well around 8-900 ppm. I tried growing with it and failed miserably when I first started growing.
As far as getting an RO set up, you want to keep that separate from your hydro system. I had a 55 gallon water storage barrel that I converted into a storage vessel for my grows. I have a submersible pump in the bottom of the barrel and just pump water out of there when I need it. You can plumb that thing to your res with a float shut off valve to automatically top off your res if you wanted to do that. You would need two of those valves, one in your res and one in your RO storage tank so it shuts off when full too.