I wasn’t aware of that. I haven’t had any issues and the swamp cooler at my place is old. It’s very dry here, but I guess if you were to not run the cooler for

I wasn’t aware of that. I haven’t had any issues and the swamp cooler at my place is old. It’s very dry here, but I guess if you were to not run the cooler for a while the water may sit and you could see stuff start to grow in it. If the water is running 20 hours a day I’d be skeptical that anything would settle there but I could be wrong. As soon as we stop using it for the season I drain the water out of the reservoir.