My 300 gallon preform has clear water but I have this brown slimey film
on all the sides and all the rocks and plastic plants. Its not green. If
I wipe it with a papertowel it looks just like poop..Yuk It staines the
papertowel brown. Not green or red. I have a uv light and a large
bio.mech filter. The fish are healthy. Any ideas? Thank you