I will begin this post with "Forgive me Father for I have sinned"....As I posted earlier I am new to this forum and have a brand new pond....I had said I wasn't going to put any fish in until spring....but temptation got the best of me and I went to Petsmart and bought a 4" Butterfly Koi....the little guy was doing great for two days....the next day he disappeared....not in the skimmer...couldn't find him in the pre-filter basket...I had to go out of town for 7 days, when I came back my pond is green with floating algae...I found his remains in the pre-filter....not seeking absolution or penance....lol.....just advice on how to clear it up....Jimmy