Reefnewbie
Is your water "yellowish" from built-up phenols, tanins, organics, etc.
Is your water "cloudy" from suspended organic detritus, fine oolitic sand, fine air bubbles, etc.
Is your water "greenish" from algae blooms, asexual caulerpa, etc.
Carbon is very good at removing the phenols, tanins, etc. in the water (plus other goodies). Polyfilter is another excellent organic compound remover, Chemi-pure is another -> all of these won't adversely affect your reef tank.
Ultra-violet will not generally clear any water, except "greenish" algae (or micro-organism cloudy tanks).
Ozone is VERY good at cleaning the water (so is diatom filters, but they can't complete with O3).
Ozone used correctly (dosage / contact time / removal / system placement)is best method to "polish" water.