Pool cage
Also called: screen enclosure, pool enclosure, lanai screen, pool screen.
A pool cage is a screen enclosure over a pool: aluminum frames with screen mesh stretched across them. It keeps most leaves, windblown debris and biting insects out, and the Florida Solar Energy Center measured a standard screen blocking 30–40% of the sun's energy on a clear day.
Why it matters
That blocked sun cuts both ways. Less UV reaches the water, so a caged pool holds chlorine better, and Trouble Free Pool says a pool under a cage does not need as much CYA as one in full sun. But a solar pool heater needs roughly a third more panel area under a cage, solar-charged skimmers charge slower, and fountains and evaporative coolers underperform because the cage cuts the breeze at the water. The screen is a consumable, and there is no single best mesh: cages mix them by panel. A cage adds a measure of child and pet safety but is not a substitute for a code-compliant safety fence.
In numbers
Standard 18x14 fiberglass screen typically lasts about 5–7 years in Florida sun. Polyester Super Screen is commonly quoted by installers at 20+ years of service.