My Pool Turned Green — Now What? A Step-by-Step Fix

You walked out to your backyard and found something that no pool owner wants to see: your pool is green. Maybe it happened gradually while you were busy, or maybe it seemed to turn overnight after a heavy rainstorm. Either way, don't panic — a green pool is fixable, and with the right approach, it can be crystal clear again in days.

Here's exactly what causes green pool water, how professionals restore it, and what you can do to make sure it never happens again.

Why Did Your Pool Turn Green?

Green pool water is caused by algae — specifically, free-floating green algae that thrive in warm, poorly sanitized water. In Brevard County's subtropical climate, algae can bloom incredibly fast. Here are the most common triggers:

• Chlorine dropped to zero: This is the #1 cause. Without adequate free chlorine (1–3 ppm), algae has nothing stopping it from multiplying. This can happen from a pump failure, running out of chlorine tabs, or heavy rain diluting your water.
• Pump or filter failure: If your circulation system stops running, stagnant water becomes an algae breeding ground within 48–72 hours in Florida heat.
• Heavy rainstorms: Summer thunderstorms introduce phosphates and nitrates (algae food), dilute chlorine, and drop pH — a perfect storm for algae blooms.
• Stabilizer (CYA) too high: Cyanuric acid protects chlorine from UV degradation, but if levels get above 80–100 ppm, it actually locks up chlorine and makes it ineffective. This is extremely common in Florida pools.
• Extended absence: Left for vacation without pool service? Even a week without maintenance in summer can lead to a green pool.
• Phosphates: Fertilizer runoff, decaying leaves, and certain pool products introduce phosphates that feed algae growth.

How Bad Is It? The Green Pool Scale

Not all green pools are created equal. Professionals typically categorize them by severity:

• Light green / teal: You can still see the bottom of the pool, but the water has a noticeable green tint. Early stage — this is the easiest to fix. Caught early, this might only need a heavy shock treatment and a day or two to clear.
• Dark green / opaque: You can't see the bottom. The water looks like pond water. This is a full algae bloom that requires a multi-day treatment process including super-shocking, brushing, filtration, and possibly partial water replacement.
• Black-green / swamp: The pool looks like a swamp. There may be frogs, mosquito larvae, and thick organic matter on the bottom. This requires the most intensive treatment — potentially draining, acid washing, and completely rebalancing.

Step-by-Step: How Professionals Fix a Green Pool

Here's the process that professional pool technicians use for a green-to-clean restoration:

Step 1: Initial Assessment — Test the water chemistry to understand what went wrong. Check pH, chlorine, CYA, alkalinity, and phosphate levels. Inspect the pump, filter, and other equipment to make sure everything is operational.

Step 2: Remove Debris — Net out all visible debris: leaves, sticks, bugs, and any organic matter on the bottom. This is important because organic debris consumes chlorine and feeds algae. In severe cases, a pool vacuum may be used to waste (sending water to drain rather than back through the filter).

Step 3: Brush Everything — Aggressively brush all pool surfaces: walls, floor, steps, and behind ladders. Algae clings to surfaces, and brushing breaks it loose so chemicals can kill it. This step is critical and often skipped by DIYers.

Step 4: Super-Shock the Pool — Add a massive dose of liquid chlorine (sodium hypochlorite) to bring free chlorine levels to 20–30+ ppm. This is called "super-shocking" or "SLAM" (Shock Level and Maintain). The exact amount depends on pool size and CYA level — higher CYA requires proportionally more chlorine.

Step 5: Run the Filter Continuously — The pump and filter run 24/7 until the water clears. Dead algae makes the water cloudy (gray-white), and the filter captures it. The filter will need to be cleaned or backwashed multiple times during this process — sometimes daily.

Step 6: Maintain Chlorine Levels — This is where patience matters. Chlorine must be maintained at shock level until the water is clear and holds chlorine overnight without dropping significantly. This can take 2–5 days depending on severity. More liquid chlorine is added as needed.

Step 7: Final Balance — Once the water is clear and holding chlorine, adjust pH, alkalinity, and stabilizer to normal operating levels. Perform a final filter cleaning.

How Long Does It Take?

Realistic timelines for green-to-clean in Brevard County:

• Light green: 1–2 days
• Dark green: 3–5 days
• Swamp-level: 5–10 days, sometimes requiring partial drain and refill

Be skeptical of anyone who promises overnight results for a truly green pool. Killing algae is fast — clearing dead algae from the water takes time and filtration.

What Does Green-to-Clean Cost?

In Brevard County, professional green-to-clean service typically costs:

• Light green: $150–$250
• Dark green: $250–$400
• Severe / swamp: $400–$700+

These costs include labor, chemicals, and multiple visits. The main expense is chlorine — a severe green-to-clean can require 10–20+ gallons of liquid chlorine. If equipment repairs are needed (e.g., a broken pump that caused the problem), those are additional.

Compare that to the cost of weekly maintenance ($125–$150/month) that prevents this from ever happening. Green-to-clean is almost always more expensive than the months of maintenance that would have prevented it.

Can You DIY a Green Pool?

You can try, but there are risks. The most common DIY mistakes:

• Not using enough chlorine: Under-shocking wastes money because the algae survives and you have to start over. You need to hit shock level based on your CYA — not just dump in a bag of granular shock.
• Using the wrong products: Pool store "algaecide" products are largely ineffective for an active bloom. Liquid chlorine (bleach) is the workhorse for green-to-clean.
• Not running the filter enough: The filter must run 24/7 during treatment. And it must be cleaned repeatedly — a clogged filter stalls the entire process.
• Ignoring CYA levels: If your cyanuric acid is above 80 ppm, even massive amounts of chlorine won't work effectively. You may need a partial drain and refill first.
• Getting discouraged and draining: Some homeowners get frustrated and drain their pool. In Brevard County with our high water table, draining a pool can cause it to literally pop out of the ground. Never drain a pool without professional guidance.

How to Prevent Your Pool From Turning Green Again

Once your pool is restored, here's how to keep it that way:

• Maintain consistent chlorine levels: Keep free chlorine between 2–4 ppm at all times. Weekly professional service ensures this.
• Monitor CYA levels: Keep stabilizer between 30–50 ppm (60 max for saltwater pools). If it creeps too high, a partial drain and refill is the only solution.
• Run your pump adequately: 8–10 hours minimum daily in summer, 6–8 hours in winter. Proper circulation is essential.
• Address rainstorms: After heavy rain, check your chlorine or let your pool tech know. A quick chlorine boost prevents post-storm algae blooms.
• Don't skip service: Even one missed week in Florida summer can lead to the beginning of an algae problem.
• Keep phosphates low: Regular testing and treatment keeps phosphate levels in check, starving algae of nutrients.

A green pool isn't the end of the world — but it is a sign that something went wrong with your maintenance routine. The best way to avoid it is consistent, professional weekly care.

Need help with a green pool? Orbit Pools offers green-to-clean service across Brevard County. We'll assess your pool, give you an honest quote, and have it sparkling again in days. Contact us for a free assessment.