1988? Wow.... talk about a mature tank!55 gallon tank started about 1988
ammonia 0 nitrite 0 nitrate 40 don't have phosphate level
dual tube fluorescent light no ferts
can't seem to get a good picture of it
starts out as small red dots then grows till it covers everything
scrapes off hard with razor blade will try to get better picture
started a few years ago maybe came in on a plant?