I have decided to build a saltwater mixing station with an RO/DI filter. I’ve looked around at different RO/DI systems, some new and some used, and I’m getting a little confused. My plan was to buy a simple, 4-stage system from BRS (picture 1). But, on several different used equipment sites I’ve seen listings for “BRS 4-Stage RO/DI System” with A LOT more equipment attached to them (example picture 2). So, can I use the simple filter in the first picture, or do I have to add more things to the BRS 4-stage to make it work properly?