Pool Algae Won't Go Away? Here's What I'd Check First

If you’ve shocked your pool, brushed it, added algaecide, shocked it again — and that algae is STILL there — you’re not alone.

This is one of the most common things people come into our store frustrated about.

And usually my first question isn’t:

“What algaecide did you use?”

It’s:

“What does your water test say?”

Because if algae keeps coming back, there’s usually a reason.

Before you dump another bottle of something into your pool, here’s what I’d check.

1. Do You Actually Have Enough Chlorine?

This sounds obvious, but I see it all the time.

Someone tells me:

“I shocked it yesterday.”

Okay — but what is your chlorine today?

Adding shock and having an adequate chlorine level are two different things.

Algae creates a chlorine demand. Sunlight, swimmers, rain, debris and other contaminants can also eat through chlorine.

So don't just tell me what you put in the pool.

Test what’s actually in the water now.

2. Check Your Stabilizer

Your stabilizer — also called CYA or cyanuric acid — matters more than a lot of new pool owners realize.

Too little stabilizer and sunlight can burn through your chlorine quickly.

Too much stabilizer can mean you need a higher chlorine level for it to be effective.

This is why blindly adding more shock isn't always the answer.

We need to know what we're working with first.

3. Check the pH

Your water can look like a science experiment when several things are out of balance at once.

Before throwing five different chemicals at it, get a good water test.

I want to know your:

• Free chlorine

• Total chlorine

• pH

• Total alkalinity

• Stabilizer/CYA

• Calcium hardness

Depending on what's happening, I may also want to know your phosphates and metals.

The numbers tell a story.

That's basically what water testing is — figuring out what the water is trying to tell us.

4. Brush the Pool. Yes, Really.

I know. Nobody wants to hear this one. 😂

But chemicals alone aren't always going to remove algae that's hanging onto your walls, floor, steps, ladders or other surfaces.

Brush it.

Pay extra attention to:

• Corners

• Steps

• Behind ladders

• Around lights

• Under returns

• Areas with poor circulation

If you keep treating the water but never disturb the algae that's attached to the pool, you're making the job harder.

5. Your Filter Has to Help You

Killing algae is only part of the battle.

You've also got to get it out of the water.

If the pool goes from green to cloudy blue or gray after treatment, that can actually mean you're making progress. Now your filter has a whole lot of work to do.

Keep an eye on your filter pressure.

Backwash or clean the filter when needed, and make sure your pump is actually circulating water properly.

If your filter is dirty, clogged or not working correctly, you can keep adding chemicals and wonder why the pool never clears.

6. “But My Water Is Clear. The Algae Is Just Stuck to the Pool.”

Yep.

I hear this one too.

If your water is crystal clear but you've got yellow, greenish or dark patches that keep showing up on the surfaces, don't assume the entire pool needs the same treatment as a green swamp.

We need to figure out what the stuff actually is.

It could be algae — but staining, metals, pollen and other problems can sometimes look similar.

That's when the details matter.

Does it brush off?

What color is it?

Where does it keep appearing?

Does it come right back?

Those clues help narrow it down.

7. Not All Algae Acts the Same

Green algae is what most people picture when they think of an algae-filled pool.

But there's also mustard/yellow algae, which can be especially aggravating because it likes to come back.

And then there's black algae, which is a different animal altogether and can be particularly stubborn on porous pool surfaces.

That's why I don't love giving someone an algae treatment without knowing what they're actually dealing with.

Identify the problem first. Treat it second.

You'll waste a lot less money that way.

8. What About Phosphates?

Phosphates can be a food source for algae, so they're worth looking at when you have an algae problem that keeps returning.

But here's the important part:

A phosphate remover isn't a substitute for proper sanitation.

I don't want you chasing one number while ignoring chlorine, circulation, filtration and the rest of the water chemistry.

Look at the whole pool.

9. Don't Just Keep Adding Stuff

This might be the biggest thing I want you to take away from this.

When a pool isn't cooperating, the natural reaction is:

ADD SOMETHING.

Then that doesn't work, so we add something else.

And something else.

Before long, you've spent $150 and still don't know what the original problem was.

Stop.

Test the water.

Look at the pool.

Check the equipment.

Then decide what it actually needs.

So What Should You Do Right Now?

If you're standing outside looking at algae and wondering where to start, here's what I need to know:

What does the algae look like?

Is the water clear, cloudy or green?

Does the algae brush off? Does it cloud when you hit it with the brush?

What kind of pool do you have?

How many gallons is it?

And most importantly:

What are your current water-test numbers? I can test your water in the store. Find a pool store that you trust to read your water sample. This is key.

Give me those things and we've got somewhere to start.

Because most of the time, your pool isn't impossible.

We just have to figure out what it's trying to tell us.

Just the Water Tester

Yep. Just the water tester. 😉

Got a pool problem? Let's figure it out.

Contact

The Family Spa & Pool Place

732 East Stone Drive

Kingsport, TN 37660

Phone & Email

familyspas@aol.com

(423) 765-1330

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