AIR CONDITIONER! I don't know about a swamp cooler's humidity production; I'd be skeptical about using one around cannabis plants for that reason. Why not install an AC? If that's your grow room, it's worth the investment; it may be a necessity with global warming. This is why I bought some solar panels around 5 years ago, because I knew electricity costs were going to go up. Another reason why I'm firmly committed to indoor growing...