These have started appearing on my piece of bog wood. They rub off easy enough, but keep coming back. It's growing quite quickly and looks a bit like cotton wool. Is it algae and if so how do I get rid?
It's either bacteria or fungus (most probably fungus), it'll run it's course about a week or so (manual removal will speed it up) fish will be safe with it in it's tank.
I had just 4 threads of it on my large piece of bogwood it looked just like it had been wiped with cotton wool and some had snagged on the rough bits, Previously on earlier set up I removed the wood scrubbed it away and replaced it in the tank only to see it grow back in a few days (and this was on wood that had been scalded with boiling water on several occasions) If it persists or becomes a real issue perhaps a treatment of API Melafix would help speed things up still further