This is the cover I purchased this year. I had some before, but my blue one cracked
Blue Devil B8481 Pool Light Lens Cover, Fits Amerlite Underwater Lights, Plastic, 7.5 inch Diameter
As far as color goes, Green makes your pool look like algae is growing. Red makes it look like you are swimming in blood. Blue is what you want. Remember to take teh cover off when you close yoru pool for the winter.