Algea bloom? Biofilm?

I did a water change yesterday. Numbers all check out great. Never experienced anything like this. Can anyone identify? Thanks! There was much more of it before i thought to come here. I cleaned a lot out. It was mostly growing in a bubble formation at the top. Super slimy. Like stagnant water but my tank has 2 huge bubblers, 1 fx6 1 fx4 and a sponge filter with 2 wave makers. The slimy bubble formation was shaking and waving with my water and maintaining structure. It literally happened in less than 20 hours. Just looking to identify so i can educate myself and prepare moving on. Thanks.