Free RODI membrane life calculator. Enter tap TDS + RODI usage, predict when to replace the RO membrane and DI resin. Save money by replacing only when needed.
Reverse Osmosis (RO) membranes are rated to reject 95-98% of dissolved solids. Lower rejection = membrane is failing. DI resin polishes the remaining solids to 0 TDS; resin exhausts based on cumulative gallons through it.
Browse the full calculator library for tank stocking, water change, dosing, PAR, electricity cost, heater sizing, CO2 BPS, salt mix, and more.