I use a high pressure fog system and it provides all of the humidity and evaporative cooling for my 200 square foot greenhouse. On a summer day when it is 40degC and 20% humidity outside, to keep the greenhouse at 30degC and 60% humidity, the fog system will run nearly continuously consuming 7 gallons per hour of RO water.
My RO system was capable of producing 8 gallons per hour of RO water but I have recently increased that to 12 gallons per hour.