Fuzzy weird stuff in my tank?

I got a 150 gallon tank. 2 tiger oscars and 3 clown loaches and 1 pleco. Fairly new setup. its about 4-5 days old. it was cycled with ornaments in place. The logs are real and they were previously in the tank from the guy i bought it from. i have owned many a fish tank before but this is the biggest one i have owned. this is also the first time i have ever seen some weird fuzzy stuff on the top of my wooden logs. im uming its algea but i have never seen algea form that quickly in a new tank. Any advice?