Pls excuse my ignorance. I know the check valve, in the direction you've documented it, will keep water from flowing our of the line if something happens to your dosing setup. But can it also keep fluid from being sucked out of the fert lines?
I did't know a check valve could do that. And even if it won't, the peristolic pump should act like a shut off valve when it is not moving, and not allow anything to flow thru it. In either direction.
Steve - 33g reef and a 180g planted in need of a re-scape.