I use a swamp cooler for almost every fermentation. Got a large 'muck bucket' from Tractor Supply, put the fermenter in that and add a water bath. The temp in the fermenter will equilibrate to the temp of the water bath, and help keep it steady. I do take the temp of the water bath twice daily and adjust it by adding 1/2 gallon ice bottles to cool if necessary and add an aquarium heater if needed to warm. With this setup I regularly do lagers in the fall/winter and ales the rest of the year.