I'm very new to chickens (have had them 10 days). I live in Florida and since I've had them we have had nothing but rain and I'm having a big problem. All day the run is fine but when I wake up in the morning there is this fluffy white stuff growing that looks like cotton. I'm sure it can't be good for the birds. Can someone tell me what it is and how to keep it from coming back? I do scoop it all out and have added some sand to the dirt to help keep it away but while it lessens the problem it is still coming back. As a side note, we've lived here for several years and have never seen this growing in any other part of our yard. Please help!