this stuff is taking over one of my tanks. it's hard, like calcium deposits, and it won't scrub off like other algae. it needs to be scraped off with a razor. it started off as one small spot growing on a rock and has been spreading.
I had the same stuff on my 125 i bought, took me forever to figure out to use a razor. It apparently will spread because an entire 125 and it's content were covered. Not sure if it's algae but I'd love to know too. I looked it up but could never find any info
Is this a salt or freshwater tank? That looks like stuff I've seen in saltwater tanks before, when purchasing them used. Is this a new or used tank you have setup?
it's freshwater. had it running for years... if i had to guess, i'd say about 4-5 years.
it's kinda weird; i only had one little spot on one rock for a long time, close to a year, then it took off about 6 months ago covering about 1/5th of the tank.