For 2 years now, i've had one brown floater in my left eye, and a few clear ones in the right. what would cause that one to be brown instead of clear?

Floaters: Floaters are normal, occur at a younger age in active people or with nearsightedness. It is caused by light hitting " debris" in the fluid inside the eye. You see the shadow cast onto the back of the eye. The more dense the particles the darker the shadow. Clear circles can sometimes be actual blood cells as opposed to floaters. Again, normal unless associated with flashes of light.

Denser material: Floaters usually are caused by the condensation of collagen fibers which make up the matrix of the vitreous gel. The denser the clumps of collagen, the more opaque and darker the floater. Vitreous floaters typically develop as the eye ages and the gel undergoes a process called syneresis where pockets of water develop and cause collapse of the collage gel and clumping of the collagen fibers.