The Clear Cover is the transparent plastic section which shields the lighting tubes in the canopy from water splashes and spray etc. These frequently become scratched and scuffed over time reducing the amount of light which penetrates the water’s surface. You will be amazed how much difference a new one can make.
These are the little springy steel clips used to secure the clear acrylic lighting cover in place on the Aqua One 620 and 620T. The clips are frequently subject to corrosion but thankfully easily replaced. Just pop the old ones off and replace with new ones.