I have a 20,00 gallon indoor pool in the UK sanitised with bromine and run year round at 87-88 degrees. I recently returned from two weeks' vacation to find a brown organic growth around the light fittings and in the grouting between tiles (especially in corners). I initially thought it was the dreaded black algae, but (i) it's easy to remove with a nylon brush (no need for steel and hard scrubbing) (ii) it's brown, not black, and (iii) it doesn't seem to have the skeletal structure a lot of people describe.
The photograph shows the organic matter (whatever it is) having rolled over into a tube in my hand - it was floating in a thin, leaf-like fashion in the water after I have brushed it from the wall of the pool
I recently had a problem with white tissue mould which I was eventually able to eradicate with some chemicals designed to eliminate biofilm and wonder whether this is any way connected with that.
Any thoughts or suggestions on what this is and how I can permanently eradicate it would be much appreciated.