Humidity Control

I have two humidifiers, a 250 lbs/hr unit and a 50 lbs/hr unit. Both of these are used to control humidity in a dryer. Both are controlled via PIDs in a RSLogix 5000 processor. Humidifier 250 is enabled with PID in Auto. If PID output is above 80% for two minutes, humidifier 50 is enabled in manual. A manual setpoint number is moved into the PID. Humidifer 250 is used to control humidity in drier. As humidity reaches setpoint and PID output starts to lower, humidifier 50 will be ramped down over a time period until PID manual output is zero. What is the best way to slowly ramp down Humidifier 50 without causing any big changes in control?