About a month ago i added a few new rocks to my tank and coraline has being slowly creeping onto it i would say over 60% of the rocks are now covered with coraline. so about a week ago i had a major nithrait boom. went from around 10 to over 80 like in 2 days. so i did a major WC but did not clean no media glass nothing.. no surface area was touched only a 80% water change. i though all was well. but i notice this morn i had a little Diatom on a rock.. i didn't think twice about i. so i left to take care of a few things.. got back like 30 min ago and all rock and glass is covered in diatom. not the coralline area but any exposed area is covered. but none on the substrait. my tank has been estrablished for over 4 years. other then the rock added like a month ago nothing new added to environment. so my question is,, well hell a few questions. why does it seem my tank is recycling? (only water bacteria was removed) why is it covering everything except my sand? and also my rocks that the Diatom its over taking. will they stay stained like that or after it cycles again. the brown diatom color will fade away and let the coralline finish covering it. I feel like im back at the beginning.