It was the same with me. It definitely didn't come on over night though in my situation, but it did come fast after I saw a little. After talking to people in the hobby near me, almost everyone has cyano
issues in the first few months of starting the tank. Mine was so bad, I had to use red slime remover. I haven't seen it since and I've added a lot since then. It was the push I needed to get it gone, I tried a lot of pwc
, blackout, and constant picking it out.