I just bought this filter brand new 5 days ago. Recently I got this greenish water problem (light green tea color). I have a 30 gal tank. I checked out my filter while siphoning water for a 20% water change. My filter was really brown and dirty. I washed bother filters with the water I was siphoning except for the bio black sponge. Is my water dirty or that is just normal with my filter. My tank only has 4 baby RBP's.