Why Your Pool Water Feels Slimy (and How to Fix It)

There are few things more uninviting than dipping your hand into your pool and feeling a slick, slimy film on the walls or steps. Slimy water is a clear sign that your sanitation system is failing and that unwanted organic contaminants are taking hold. It's not just unpleasant; it's a precursor to more serious problems like a full-blown algae bloom.

This guide will help you diagnose the reasons behind slimy pool water, explain what that slime actually is, and provide a step-by-step action plan to eliminate it and restore your pool to a clean, safe, and comfortable state.

What is the Slime? The Main Culprits

That slimy feeling is caused by microorganisms creating a protective layer. There are two primary culprits:

1. Biofilm

Biofilm is a thin, slimy layer of bacteria and other microbes that adhere to surfaces. This bacterial colony creates a protective matrix that is highly resistant to chlorine. You'll often feel it on ladders, in corners, or on pool toys left in the water. It can be present even when the water looks clear.

2. Early-Stage Algae

Before algae becomes visible and turns the water green, it starts as a slimy layer on the pool surfaces. If you run your hand along a wall and it feels slick, you are likely feeling the very beginning of an algae colony. This is your last chance to act before you have a much bigger problem on your hands.

Why Does Slime Form? The Root Causes

Biofilm and algae take hold when your pool's sanitation barrier is weak. This almost always comes down to a lack of effective chlorine, which can be caused by several factors:

• Low Free Chlorine (FC): If your active sanitizer level is too low (below 1-3 ppm), there simply isn't enough chlorine to kill the microorganisms before they can form a protective slime layer.
• Poor Water Circulation: "Dead spots" in your pool with poor water flow are prime real estate for slime and algae to grow undisturbed.
• Ineffective Chlorine due to Water Imbalance: High pH (above 7.8) can make your chlorine sluggish and unable to sanitize properly. Similarly, very high Cyanuric Acid (CYA) levels (over 100 ppm) can "over-stabilize" the water, preventing chlorine from working effectively.
• Organic Contaminants: A high load of organic debris from leaves, oils, and swimmers provides food for bacteria, consuming your chlorine and allowing slime to form.

Action Plan: How to Get Rid of Slimy Pool Water

Getting rid of slime requires a two-pronged attack: physically removing the slime layer and chemically destroying the microorganisms.

Step 1: Physical Removal - Brush, Brush, Brush!

Chemicals alone cannot penetrate the protective matrix of biofilm or algae. You must physically break it up first.

1. Take a stiff pool brush and thoroughly scrub **all** surfaces of your pool: walls, floor, steps, ladders, and behind any fittings.
2. Pay special attention to corners, crevices, and any areas where you feel the slime.
3. Remove and scrub any pool toys, floats, or cleaning equipment that has been sitting in the water.

Step 2: Test and Balance Your Water Chemistry

Before you shock the pool, test your water and make any necessary adjustments. The most important parameter to adjust first is pH.

Adjust pH to 7.2 - 7.4. Chlorine is much more effective at a slightly acidic pH. If your pH is high, lowering it before you add chlorine will make your treatment far more potent. Use our pH Calculator for accurate dosing.

Step 3: Shock the Pool

This is the chemical attack that will kill the now-exposed microorganisms. You need to raise the Free Chlorine level high enough to oxidize all the contaminants.

• Use a strong dose of liquid chlorine or cal-hypo shock. Don't rely on your salt system's "Super Chlorinate" function for this, as it's not powerful enough to overcome an existing problem.
• Use our Pool Shock Calculator to determine the correct amount based on your pool volume and CYA level. For a slime problem, it's better to err on the side of a stronger shock.
• Shock the pool at dusk or at night to prevent the sun from destroying the chlorine before it can do its work.

Step 4: Circulate and Filter

Run your pool pump continuously (24/7) for at least 24 hours after shocking. This ensures the chlorine is distributed throughout the entire pool and allows the filter to capture the dead organic matter.

Step 5: Follow-Up and Prevention

• Brush Again: Brush the pool again 12-24 hours after shocking to dislodge any remaining stubborn spots.
• Test Chlorine Levels: Monitor your Free Chlorine level. It will be high after shocking. Wait for it to return to a normal range (3-5 ppm for salt pools) before swimming.
• Clean Your Filter: Once the problem is resolved, clean your filter thoroughly (backwash or cartridge clean) to remove the dead contaminants you've filtered out.
• Maintain Proper Chemistry: The key to preventing slime is consistent maintenance. Keep your Free Chlorine in the proper range at all times, ensure your pH and other chemicals are balanced, and run your pump long enough each day for adequate circulation. Use our Pool Salt Calculator to ensure your salt level is always optimal for chlorine production.

By following these steps, you can effectively eliminate that slimy feeling and ensure your pool remains a clean, safe, and inviting place to swim.