I found a few patches of suspicious looking brown mats in my 100g. I fought these back in December / January and won (or so I thought!). I confirmed the diagnosis with a microscope: Ostreopsis. I changed out the carbon in my reactor and busted out the UV sterilizer. Going to run it in the sump for a week or so and baste the rocks throughout the day. You can barely notice them, but I’d rather squash it now than lose all my coral again!
Wish me luck!
Wish me luck!