pull don’t push …. the line with a valve to be replaced by a line feeding second LitreMeter(used from fisheebill) for frag system. LM’s will (hopefully) act as check valves for each other. Intake of fresh water is blue line. Yellow and black are intakes to LiterMeters and clear tubing is output from LiterMeter headed off to the tank. Float valve to the right is safety shutoff for RO unit.