Within the past couple of weeks I have gotten growing on my hydroballs in my WTF tank. I even started getting mushrooms. I've had the tank 5 years and replanted it once a couple years ago. I have never had an issue. I think my kids spilled water in there when they were filling the bowl. Humidity is usually around 50% and temp around 78-80. I have been adding isopods and springtails daily. Not sure they are helping at this point.