I've got the 300gpd pumped RO-man. After 18months the pump packed up ( it was the one in the metal box) RO-man told me they were only guaranteed for 6 months, and advised me to buy their new bigger pump (about £75 from memory) It's preset at a constant 75psi regardless of input pressure and I get the same production rate regardless of temperature, mains pressure etc. So far working fine - I need to make about 7-800lt/day for two of us. Takes about 12 - 14 hours. Input TDS 230-260 output 003
Cheers,
Ian