Disolved Gases such as AMMONIA (NH3) will NOT normally be rejected by an RO membrane. When NH3 is in a environment where the temperature is LESS than 104 Degrees F and the PH is LESS than 7, then more than 95% of the NH3 will convert to NH4 and the membrane's rejection should be better than 98%. However, if both parameters are allowed to increase, the amount of ammonia will also increase, accompanied by a corresponding decrease in rejection by the RO membrane. NITRATE ion rejection is dependent on a combination of factors: PH, flux, ionic strength, counterion mix, and membrane type. Tyically nitrate rejection by the RO membrane ranges from 85% to 98%.