doesnt take much surface agitation, but the led is important. keep in mind yes 225 is a pretty good chunk of change, light output is similar to a 150w metal halide but dont need to replace bulbs and run 1/5th the energy. should pay for itsself within a year over T5 or metal halide. had decent shimmer with led spotlights on other tanks, but never seen the rays of light like well the sun. only complaint is light spill due to round lighting area and a rectangular tank.