I have an RO/DI unit that is probably in need of new filters and DI resin. The RO membrane is still under pressure and is only a year old. I run it periodically just to keep it from getting stagnant. I also have a refractometer, TDS meter, timers (digital and regular), small LED retro lights, a DIY auto topoff with aqualifter pump and anything else lying around is yours for $80 OBO.