How Do I Remove Metals from My Pool Water?

Use a metal sequestrant to bind metals like iron and copper, preventing stains and discoloration.

Why Metals in Pool Water Are a Problem

Metals like iron, copper, and manganese often enter your pool from well water, corrosion of equipment, or certain algaecides. They may be invisible at first, but once you add chlorine or shock, they oxidize and cause stains, discoloration, or cloudy water.

Common Metal-Related Issues:

• Brown or rust-colored stains (iron)

• Blue-green discoloration (copper)

• Black or purple stains (manganese)

• Green water after shocking

• Cloudiness after chemical treatment

Over time, unaddressed metal levels can lead to buildup in plumbing, filtration equipment, and around tile or vinyl liners. Stains may become difficult or impossible to remove without draining or resurfacing.

How Metals Get into Pool Water

Understanding where metals come from helps you stop them before they build up.

• Fill water: Well water is the most common source and may already contain metals in dissolved form.

• Old plumbing: Copper pipes and bronze fittings slowly corrode, releasing metals.

• Equipment corrosion: Pool heaters, pumps, and rails can deteriorate when water chemistry is off.

• Chemical use: Some older or low-cost algaecides contain copper as an active ingredient.

• Low pH: Acidic water accelerates corrosion, pulling metals from pool components.

If you are filling or topping off from a hose or well, it's smart to test your source water before it enters the pool.

Testing Your Pool for Metals

Before treating, confirm whether metals are the issue. Don’t assume cloudiness or stains are always from algae. Metals behave differently and require a separate solution.

How to Test:

1. Use a test kit or test strips specifically for iron, copper, or manganese.

2. Bring a water sample to a professional pool store for digital testing.

3. If metals are confirmed, determine the type and concentration (usually measured in ppm).

Also note when symptoms appear. Green water immediately after shocking usually indicates metals, while gradual green tints are more likely algae.

Step-by-Step: How to Remove Metals from Pool Water

1. Stop Adding Chlorine or Shock

Adding chlorine to metal-rich water causes oxidation. This is what turns water green or makes stains suddenly appear.

• Pause all sanitizers and do not shock until the treatment is done.

• Allow chlorine to drop below 1 ppm for best results.

2. Lower the pH Level

Lowering pH helps keep metals in suspension.

• Aim for a pH of 7.2 using muriatic acid or dry acid.

• Do not go below 7.0 to avoid damaging pool surfaces.

3. Add a Metal Sequestrant

Sequestrants bind metals and prevent them from staining surfaces.

• Choose a phosphate-free, non-foaming formula labeled for pool use.

• Calculate your pool volume to determine the right dosage.

• Pour slowly around the perimeter with the pump running.

4. Filter Continuously

Run the pump for 24 to 48 hours straight to circulate and trap the sequestered metals.

• Clean the filter halfway through the process.

• Keep your skimmer basket empty and your pump strainer clean.

5. Clean or Backwash the Filter

Once metals are trapped, remove them from the system.

• For sand or DE filters, perform a full backwash.

• For cartridge filters, remove and rinse thoroughly with a hose.

6. Retest and Rebalance

After metals are reduced:

• Raise pH back to 7.4–7.6.

• Adjust alkalinity if it was altered.

• Bring chlorine levels up slowly, starting with small doses.

What Not to Do

Avoid common mistakes that make metal removal harder:

• Don’t shock the pool while metals are still present.

• Avoid metal-based algaecides if copper or iron levels are already high.

• Never ignore small stains assuming they’ll fade. They often set in deeper over time.

Preventing Metals from Returning

Keeping your pool metal-free is an ongoing process, especially if your source water is the culprit.

Use a Hose Filter

A hose-end filter captures metals before they reach the pool. This is essential if you’re using well water or live in areas with high mineral content.

Maintain Water Balance

Consistent chemistry reduces corrosion and metal leaching:

• Keep pH between 7.2–7.6

• Maintain alkalinity between 80–120 ppm

• Monitor calcium hardness and avoid aggressive water conditions

Test at least once a week, especially after storms, water additions, or high bather loads.

Add Sequestrant Regularly

Metals may enter the pool in trace amounts all season. Regular doses of a sequestrant keep them suspended and non-reactive.

• Follow label directions for a weekly or monthly maintenance schedule.

• Increase dosage if topping off with suspect water.

Inspect Metal Fixtures and Equipment

Ladders, handrails, pool lights, and heaters should be checked annually. If they show signs of corrosion or rust, replace them or treat them with a protective coating.

Use sacrificial anodes to divert corrosion from critical components. These inexpensive zinc devices absorb damage from electrolysis before it affects your pump or heater.

When to Call a Professional

Not all metal problems can be handled with a bottle of sequestrant and a test strip. Some conditions require deeper fixes or specialized treatment.

• If your stains won’t fade after repeated treatments

• If metal levels remain high despite filtration

• If water changes color each time you shock

A pool technician can run advanced diagnostics and apply high-strength stain removers or perform acid washing for severe surface staining.

They can also help you identify hidden plumbing or equipment issues that are contributing to recurring problems.

Clear Water, No Metal Surprises

Metals in pool water might be invisible at first, but the damage they cause is anything but. With the right testing, treatment, and routine care, you can keep your water crystal clear and free from stains. Stay on top of balance, watch for signs, and take action before metals turn your maintenance into a bigger job than it needs to be.