Weird green tint in water, Is it algae or something else?

J

Jacob Foster

Member
I noticed my pool water’s starting to look a little greenish, but it’s not super cloudy yet. I’ve been keeping chlorine levels pretty normal, so I’m not sure what’s going on. Could it still be algae even if the water’s mostly clear?

I gave the sides a brush and ran the pump longer yesterday, but I don’t see much of a difference. No big patches or anything, just that odd green tone.

Should I go ahead and shock it now, or wait until it gets worse? Not sure if I’m jumping the gun or not.
 
If your water’s starting to look greenish, even if it’s still mostly clear, that’s usually the early signs of algae starting to grow. Algae can start to tint the water before it turns into the full cloudy mess we all dread. I’d go ahead and shock it now rather than waiting it's a lot easier to clear up in the early stages than once it spreads. Also double-check your pH and stabilizer levels because if either one is off, your chlorine won’t work as well, even if the test shows your levels are “normal.” I’d keep brushing daily for a few days and run the pump longer until the green tint disappears.
 
I had something like that a while back, green tint but crystal-clear water, and it turned out it wasn’t algae at all. It was copper from my fill water reacting with chlorine. I didn’t even know metals in water could cause that until someone at the pool store tested it for me.

If you’ve got an old heater or copper pipes, or even if you’ve added an algaecide recently (some of them have copper in them), it can leave a green tint that looks like early algae but isn’t. I ended up using a metal sequestrant, and it cleared up in a couple of days. It might be worth testing for metals just in case before throwing in more chlorine.
 
Hey Jacob,

Even if the water looks mostly clear, a green tint can be early algae, or it could be metals like copper in your water reacting with chlorine. I’d first test for metals; if that’s clear, go ahead and do a shock treatment now. Keep brushing and run your pump longer until the tint disappears, and double-check your pH and chlorine levels so they’re actually effective.
 
I ran into that same greenish look once, and in my case it ended up being high phosphates feeding a light algae bloom even though my chlorine was “normal.” The water never got cloudy, just had that odd tint. Once I treated for phosphates and kept brushing daily, the color cleared fast. Might be worth checking that along with metals before you decide on the next step.
 
I've seen the water turn a little green too, and it's usually a sign that algae is starting to grow. Check your pH and stabilizer levels, and make sure everything is balanced. If needed, go ahead and shock the pool.
 
If your water has a green tint even though it is still mostly clear, I usually do not wait until it gets worse. I would retest first (chlorine, pH, and CYA if you can), brush the walls and floor, run the pump longer, and if it looks like early algae, I would shock now while it is still easy to knock out. But if your chlorine is truly holding steady and the green tint is still there, I would also consider testing for metals (copper or iron) because that can look a lot like algae too.
 
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