tan

Hi - apologies as I'm fairly new to the forum so not sure if this is covered already...have something that looks like a tan hairy moss and have no idea if it's good or bad. It's not green hair algae (at least that I know of but looks like a feathery tan stringy moss.) Anyone know what this is...

Started cycling last week, my sand was white but all of a sudden orange-ish patches are starting to form. Is there something wrong or is this normal?