I've never seen anything like that before, does it have a sent? It looks like it might be some kind of mold or bacteria colonies.

Here's a kitchen trick for getting it out though. Get a pair of strainers and put a layer or two of cheese cloth between them, then scoop up the water a little at a time and let it drain through the cloth. It might take a while, but then you'll be rid of it for a while and have a sample to take to a LFS if you wanted to get another opinion there.