I've been curious about this for a while. For those of us who are fairly strict with keeping our RODI water up, how far do you take that? I especially have nano tanks in mind here since bigger tanks have so much more volume it's likely less of an impact. When you clean your equipment (pumps, heaters, scraper, etc), do you rinse it with RO water after the fact before it goes in the tank? I've typically not bothered rinsing with RO unless it's a really porous material. Inevitably this means I'm putting trace amounts of tap water into the tank, but I've always figured it's pretty inconsequential.