Dealing with a Slimy Pool Despite Clear Water: Tips and Tricks

As a pool owner, you’re likely familiar with the routine of checking your pool’s health, ensuring it’s clean and visually appealing. But what if the water is clear yet feels slimy? This unexpected situation might leave you puzzled. Is it normal for clear pool water to be slimy, and if not, what could be causing this? In this article, we’ll explore the common reasons behind clear but slimy pool water and provide guidance on how to address them.

Key Takeaways

  • Probable Causes: Four primary reasons why your pool water might appear clear but feel slimy, including low free chlorine levels, high calcium, excessive Total Dissolved Solids (TDS), and poor water circulation etc.
  • Diagnostic Steps: Discover how to diagnose the specific cause of the sliminess in your pool, including testing pH levels, chlorine concentration, total alkalinity, calcium hardness, and TDS levels.
  • Effective Remedies: Various remedies to restore chemical balance in your pool, from shock treatments and adjusting pH levels to managing calcium hardness and TDS.
  • Maintenance Tips: Understand the importance of regular pool maintenance tasks such as debris removal, scrubbing pool walls and floors, ensuring proper circulation, and monitoring water temperature.
  • Prevention Strategies: Learn strategies to prevent future occurrences of slimy water, ensuring your pool remains clear, healthy, and inviting.

Clear But Slimy Pool Water: Reasons And Remedies

You can only fix a problem once you find the cause, so diagnosing the reasons for that slimy feel is the first step.

Reasons For Slimy Water

  • Check the pH: The ideal pH is between 7.2 and 7.6. Anything over 8 will affect the efficiency of the chlorine in the water and make it easier for algae to develop.
  • Check chlorine level: ideally, the free chlorine (FC) level should be between 1 and 3 ppm. Chlorine is the most effective weapon in the fight against algae.
  • Check Total Alkalinity: Low alkalinity results in a quick drop in chlorine, and high alkalinity can lead to increased pH, which impacts chlorine efficiency.
  • Calcium Hardness: not all kits have this test, but a possible cause of that slimy feel is if the CH is high. Look for the tell-tale sign of a white scale forming on the pool walls.
  • Check TDS level: The total dissolved solids are all the different organic and inorganic substances that get dissolved in the water, including chemicals, algaecides, stabilizers, and also things like body oils, hair lotion, sweat, and deodorants. The ideal level is between 500 and 1500 ppm. Still, it can rise to 5000 ppm before it can cause significant problems, limiting the ability of the chlorine to combat algae growth.

Remedies For Slimy Water

Restoring the chemical balance is the key to removing the slimy feeling in the water and on the surfaces of the pool.

  1. The pH level can be increased by adding an alkaline base such as sodium bicarbonate (baking soda) or sodium carbonate (soda ash). To reduce pH, add an acid such as muriatic acid or sodium bisulfate.
  2. Low free chlorine level: Shock treatment is called for if the pool is slimy because algae are already starting to become a problem, even if the water is still clear. You can take the chlorine level up to 10 ppm or even higher to kill the algae. It will return to normal levels within a couple of days, so don’t be concerned, but remember that shock treatment may cause the pH level to rise, so keep a check on that.
  3. Calcium Hardness (CH) can be reduced by what is known as a sequestering agent, which binds with the calcium to make it disintegrate more easily. The only alternative is to partially drain the pool, but this will obviously affect the balance of all the other chemicals in the water. If the source water has a high calcium content, this isn’t a solution anyway.
  4. TDS level: There are some very costly ways of reducing the TDS level in the pool, including reverse osmosis and micro-filtration using membrane filters, but these aren’t practical options for most pool owners, and the only other solution is a partial draining of the pool and refilling it with clean, uncontaminated water.
  5. Remove debris from the surface: although the water is clear, the sliminess is proof that it’s full of bacteria, and algae are going to turn it green in days. Now that you’ve balanced the chemistry, it’s time to look at the pool itself. The first step is to use a net to remove any debris from the surface that would provide nutrition for the algae that threatens the pool.
  6. Scrub the pool walls and floor: If the water feels slimy, you can bet the sides of the pool and the bottom are beginning to feel that way, too. Using a stiff-bristled pool brush, remove all signs of algae spores from the walls and floor, give it a short time to settle, and then vacuum to waste.
  7. Circulation is the key to the whole process of keeping your pool water not only clear but free of bacteria and algae. If the chemistry is right, and the filtration is below standard, the contaminants that feed algae are going to stay in the pool and cause havoc. So it’s vital that the filter is clean, the skimmer and pump baskets are empty, and water can circulate freely and at full pressure.
  8. Temperature: the warmer the water, the faster the chlorine level drops, and the easier it is for algae and bacteria to take control. After a few hot days, it’s essential to check your pool chemistry and do everything I’ve mentioned. In addition, if you can cool the water with an aerator, bubbler, spray, or fountain, that too will help control that slimy feel that can arise overnight.


Clear, clean water doesn’t necessarily mean that it’s perfectly healthy and that slimy feel is a warning that bacteria and algae are present and about to take over. Catching them early by diagnosing the reason and then applying the various remedies available will ensure that clear doesn’t turn to cloudy, blue doesn’t become green, and the slimy feel disappears. Good luck, and enjoy your sparkling, non-slimy pool!