Flowclear Solar Pool Cover 4.88 m. Keep water and heat in and debris, leaves, and trash out of your pool with this Flowclear Solar Pool Cover. Above ground swimming solar pool covers create a greenhouse effect in your pool. Solar covers also prevent water evaporation caused by dry winds, or free-chlorine loss caused by UV rays. These covers are designed to keep water and heat in, but debris out. Extend your swimming season with a Flowclear Solar Pool Cover. Fits 18'/5.49m diameter Fast Set, 16'