What I have is what Solarfall has. Yote has something different. BTW, there are brown, green and red algae and red has the most species. Its very easy to confuse the different types.
I tried blow torching rock in a 5G bucket last night. The bucket had used change out water and the rock in there was out of the water for only a couple minutes. I rinsed the rock well put it back in. Today the bucket stinks of charred something and there is a nasty spike of nitrites and nitrates both. I did not check ammonia. I think I may back off on the blow torch plan. Maybe a steel brush and rinse the rock in used change out water.
Err yeah if you have nitrites you probably have ammonia. I'd definetly back off on the blow torch. You probably killed a lot of micro life like that and in a tank as small as yours it could definetly set off a cycle.