It's been some time since I have been here, so I hope everyone is well.
I have a strange issue which started to happen in my tank around four weeks ago now. A little bit of background, my tank has been running now for two years - its a Nano and only 90 litres in total volume. I had got to the point where everything was perfect for perhaps the last year, the sand was white and my maintenance has been like the Swiss transport system and parameters have always been in check.
It all began when I bought a new coral, when I got it home and in the tank I saw these huge tentacles coming out of it but didn't do anything at that stage. A day later these tentacles were protruding out of some live rock where my established Star Polyp coral had grown all over. When I say long, they were about 6 inches and bristly. I did some research and it turned out to be a Bristle Star Fish. It was living within the rock and coral somehow, and the Star Polyp stopped opening over the course of the week. So I removed and dunked in RO water to get this thing out - it was huge! How I never saw it when I bought the recent coral I have no idea.
After this my star polyp never did open again, and slowly instead of opening brown dust type algae formed over this one piece of rock, and then onto the sand. I have now placed it at the top of the tank. However the brown/rust algae remains. I was worried it could be Dinoflagellates, but looking online and trying to ID it seems to be more diatoms.
I have a phosban reactor running bio-pellets, wet skim 24/7 and have a 12 hour lighting schedule on AI Prime (David Saxby Settings)
From everything I can see diatoms shouldn't be in an established tank. Could this be dinoflagellates? Anyone with any ideas or thoughts would be really appreciated as I am just lost with why/what is going on?
... I am not sure how to add an image anymore - the insert image just puts the word 'img' in brackets.