Why is my pool green but not cloudy?

Clear-but-green water is usually dissolved metal (most often copper), not algae. Algae makes water hazy and slimy; copper tints the water like tea while it stays see-through. Do the white-bucket test: if adding chlorine makes a bucket of the water darker instead of clearer, it's metal, and shocking it will only set a stain.

How do I know if my green pool is algae or pollen?

Feel and location. Algae is slimy, clings to walls and shady corners, and gets worse over days. Pollen is gritty and powdery, floats at the waterline and in the skimmer, and crumbles when it dries. Algae eats chlorine fast; pollen doesn't touch it. When in doubt: slimy is algae, gritty is pollen.

Will shocking the pool fix green water?

Only if the green is algae. Shocking clears algae, does nothing for pollen, and actively makes copper-green worse by oxidizing the metal into a stain. That's why you confirm the cause with a bucket test first. 'Shock everything green' is the single most expensive mistake in pool care.

What is the white-bucket test?

Fill a clean white bucket with pool water, add 2–3 fluid ounces of liquid chlorine, and watch for a couple of minutes. Clears up = algae. Darkens = dissolved copper or iron. No change but the surface is still green = pollen or a surface stain. It's a two-minute test that saves you days of treating the wrong problem.

Why Is My Pool Green? Algae, Copper, and Pollen, Told Apart

Before you dump a jug of chlorine into a green pool, here’s the short answer: green water comes from one of three totally different things: algae, dissolved metal (usually copper), or pollen. All three need opposite treatments. The fastest way to tell them apart is a two-minute white-bucket test. Get that wrong and you can spend a week and a small fortune making the problem worse. Get it right and you’re halfway to clear.

So let’s play pool detective. It’s more fun than it sounds, and nobody gets arrested.

The 2-minute white-bucket test

This one comes straight from the folks at Orenda, and it’s the single most useful thing you can do with a green pool:

Fill a clean white bucket at least halfway with your pool water.
Snap a photo of the starting color (your memory will lie to you).
Add 2–3 fluid ounces of liquid chlorine and stir.
Watch for 30 seconds to a few minutes and compare to the photo.

Here’s your verdict:

The water clears → it’s algae. Chlorine kills it, so it’s already fading in the bucket. Head to the green-to-clean SLAM.
The water gets darker (deeper green, brown, even black) → that’s dissolved copper or iron. Chlorine oxidizes metal, which is exactly the wrong move. Do not shock.
The water stays clear but the surface is still green → pollen (or a surface stain). Chlorine shrugs. You’ll skim and filter this one out.

The bucket already told you the truth. Don’t argue it back to “probably algae” just because algae’s more common. Slimy is algae, gritty is pollen, clear-but-colored is metal.

Culprit #1: Algae (the usual suspect)

About nine times out of ten, green means algae, free-floating plant cells throwing a bloom because chlorine dropped below the level it needs to keep them in check. The tells:

Water is cloudy or hazy green and gets worse by the day.
It clings to walls, floors, and shady corners, and feels slimy to the touch.
Your free chlorine reads low or zero: the algae is eating it as fast as you add it.

Algae is the good news scenario, weirdly, because it’s the one chlorine actually fixes. The cure is a SLAM: raise free chlorine to your CYA-scaled target and hold it there until the water clears. That’s a whole method of its own: here’s the step-by-step.

Culprit #2: Copper (the impostor)

This is the one that fools people. Copper-green water is usually clear but tinted (think weak tea sliding toward emerald) and the color sits evenly through the whole pool because the metal is dissolved, not floating. Free chlorine reads normal or high. It shows up after someone uses a copper-based algaecide, from well or fill water high in metals, or from a heater’s copper heat exchanger eroding when pH runs low.

Here’s the trap: raise the chlorine and copper-green gets worse, not better. Chlorine oxidizes the copper and can drop it out as a stain on your plaster, a permanent teal souvenir nobody asked for. So if the bucket darkened, put the shock jug down. What you actually want is a metal sequestrant (it chelates the copper so it stays invisible in solution; you’ll re-dose it periodically as it breaks down), plus stopping the source: quit the copper algaecide, balance your pH, and pre-treat problem fill water. Sequestrant hides the metal; only a partial drain-and-refill or dedicated removal media actually gets it out.

Culprit #3: Pollen (the freeloader)

Sometimes green isn’t chemistry at all. It’s springtime. Pollen blows in, floats as a fine green-yellow film at the waterline and in the skimmer, and it’s gritty and powdery: rub it between your fingers dry and it crumbles. Free chlorine reads normal because pollen doesn’t consume it. This is a physical nuisance, not a water problem: skim it with a fine-mesh net (the standard net just lets the grains sail through), run the filter, and clean or backwash afterward. A clarifier can help your filter grab the finest bits. Whatever you do, don’t shock your pool over tree sex. Save the chlorine.

Once you know what you’re dealing with

If it’s algae, you’re off to a SLAM, and the number that drives the whole thing is your free-chlorine-to-CYA ratio, which is worth understanding cold: here’s the ratio, explained without the jargon. If it’s metal or pollen, you’ve just saved yourself a week of treating the wrong problem, which is its own kind of win.

Or skip the detective work entirely: tell AL GEE what you’re seeing and I’ll walk you through the bucket test and whichever fix your pool actually needs. Free to start, no credit card, and I promise not to tell you to shock a pool full of pollen.

AL GEE is Azoolify’s AI pool expert. Every claim here traces to established pool references (the white-bucket test from Orenda and the green-water differential from TroubleFreePool), not to any product you’re being sold. When a range is in play, we start you at the low end: you can always add more.