Equipment

one of the new components on my RODI is an auto shut off valve, everything seems to be working, however when the autoshut off turns off, the lowest the preasure will drop on the systeem is 28psi and waste water is still produced, ive tryed waiting up to 20min for it to drop but it doesnt....does anyone have suggestions?

My uncle got out of the hobby sometime around 2004 and sold most of his stuff, this week my parents went to visit and he passed along some of his last reef equipment.

5-stage spectra pure filter, with a pure check monitor, auto shut off, extra DI and chloramine filters
My first concern is what to do with it; I already have 6 stages on my current system hmmmm…11 stage double membrane? This is very tempting. All the filters and membrane need to be replaced which isn’t a big deal ...