The panic that comes with a green cage
It usually starts the same way. You look up from the pool deck and realize the screen panels have green algae all over them, the frame has gone dull and streaky, and the corners look furry. The next thought is the bad one: the screens are shot and the whole cage needs rescreening.
That's a real fear, because rescreening a cage is a serious job and not a small one. So it's worth saying up front. A green cage is almost always a dirty cage. Growth on screen looks far worse than it is, and most of what you're looking at comes off.
There are exceptions and they're covered further down, honestly, because a cleaner who tells you every cage cleans up is not being straight with you. But the odds are on your side here.
What's actually growing on it
Algae and mildew, the same things that turn a north wall green and streak a roof black. Screen mesh is close to perfect for them. It's thin, it holds droplets in every opening, and there's a huge amount of surface area packed into a small panel. Water sits in that mesh long after the deck below it has dried.
The aluminum frame gets it too. Frame members are wide, flat and horizontal on the top edge, so they catch water, dust, pollen and whatever falls out of the trees. The uprights streak, the top rails go dark, and the fasteners collect their own little rings of grime. That's why a cage can read as green from a distance and grey and streaky up close.
Kickplates take it worse than anything. Those are the solid panels along the bottom of the cage, and they sit exactly where irrigation overspray, splash off the deck and water running down the screen all end up. They stay wet longer than the mesh above them and they usually carry the heaviest growth on the whole structure.
The pool itself contributes a little through splash and humidity, and the screen catches whatever blows in off the yard. Grass clippings, pollen, sand and fine dirt all end up in the mesh, and once organic material is sitting in a damp place, growth follows.
Why the shaded side is the bad side
Walk the cage and you'll find one side much worse than the rest, and it'll be the side that gets the least sun. Same rule as everywhere else on the property: whatever dries slowest grows the most.
Tree cover makes it dramatic. A cage with a live oak or a stand of pines over one corner will have a green corner and a clean corner on the same structure. The canopy blocks sun, holds humidity underneath it, and drops leaves and needles onto the top panels where they sit and rot until somebody moves them.
The wall side is the other usual offender. Where the cage attaches to the house, the panels sit in the building's shadow for a chunk of the day and get very little air moving through them. That's often the worst run of screen on the whole structure, and the wall behind it is usually on the same list, which is why cage work and house washing often get quoted together.
Why it explodes in the rainy season
Through the summer and into September the cage basically never dries out. Rain most afternoons, humidity all night, and warm temperatures the entire time. Screen that's still damp at nine in the morning has no chance.
That's why people come back in the fall to a cage that looked fine in the spring. It didn't turn green in a week. It had five months of ideal conditions with nobody standing under it noticing the change.
Top panels are the part that surprises people most. You don't look up at them from the deck, so the first time you really see them is from a second floor window or in a photo, and by then they're usually the worst panels on the cage.
Corners and fasteners are their own category. Growth collects in every joint where two frame members meet, and around every screw head, because water sits in the seam long after the flat surfaces have dried. Those are the spots still looking dirty after somebody has stood on the deck and hosed the cage down, and they're the reason a hose job never quite finishes the picture.
When it isn't dirt
Here's the honest part. Screen doesn't last forever. Florida sun breaks it down over years, and screen that's gone brittle will not come back with cleaning, no matter what gets used on it. If a panel is torn, sagging out of its spline, or crumbles when you press it, that's a repair, and a repair is a screen company's work rather than a cleaner's.
The other thing worth knowing is that a heavy layer of growth hides problems. Green mesh looks solid. Once the growth is off, small tears, thin patches, gaps at the spline and corroded fasteners become visible, and it can feel like the cleaning caused them. It didn't, it just uncovered them.
That's a good outcome even when it doesn't feel like one. It's better to find a torn panel in October than to find it when something gets in through it. If a cleaning turns up damage, you'll hear about it plainly rather than being told the cage came out perfect. There's a full explanation of how cleaning and screen condition relate in the post on whether cleaning damages pool cage screen.
What a cleaning won't do
It won't repair screen, replace panels, re-spline anything or fix a bent frame member. It won't restore aluminum that's already corroded, and it won't put color back into screen that the sun has bleached over a decade. Those are all different jobs and none of them are cleaning jobs.
It also won't keep the cage green free forever. The shade, the trees and the humidity are all still there afterward, so the growth restarts on the same cycle it always has. Cages under heavy tree cover come back sooner than cages sitting in the open, and that's just the trade for having the trees.
Common questions
Do I need new screens, or does it just need cleaning?
If the mesh is intact and the problem is color, it's dirty and it cleans up. If panels are torn, sagging, or brittle enough to break when you press on them, that's screen that's reached the end and it needs replacing. Send a photo and you'll get a straight read, including if the read is that a screen company is the better call.
Is the algae on my cage going to get into the pool?
What's growing on the mesh is surface growth and your pool chemistry handles what falls in. The bigger nuisance is that green screen means the whole enclosure stays damp and shaded, and everything under it, the deck, the furniture, the cage footers, tends to be dirtier than it looks.
How often does a pool cage need cleaning here?
Once a year suits most cages in this area, which is the usual cycle for pool cage and deck cleaning out here. Under heavy tree cover it's often sooner, and if the enclosure is on the shaded side of the house it'll show growth faster than a cage sitting in full sun. If you're only doing it every few years, expect the job to be bigger each time.
Send a few photos of the cage
Photograph the worst side, one of the top panels if you can get an angle on it, and a close up of any panel you're worried about. Pricing comes back by text, no appointment and nobody walking your pool deck to work out a number. Call or text (941) 257-8624 and you'll get an honest answer on whether it's a cleaning or a repair.