So I screwed up.
I got the HP and LP fittings mixed up when I installed my new membranes and put about 300 (or so) PSI of salt water
through the product water
out let fitting.
I ran it like this for a couple minutes but was having trouble building pressure so I stopped and looked at the membranes before realizing what happened.
I took the membranes apart and fixed everything up properly. When I started up the system again I ran it at 800 PSI and got product water
at about 1300 PPM. The quality got better with time, but very slowly, and after about an hour I was making water at about 550 PPM. I have two SW30-2540 membranes and when I checked the individual outlets they've were 750 and 350 PPM respectively (or close enough).
Since then I've tried taking the membranes about and checking all O-rings again, as well as running only a single
membrane in the system, however I can not get the product water below 900 PPM (although I have not run it for an hour like the first time, maybe only 15 minutes).
Have I ruined my membranes by putting water in the wrong way?