How to Get My Pool Back to Blue

posted by PebbleTec International in
blue pool at sunset
Pictured: Gentilli Custom Pools, PebbleSheen – Ocean Blue

It’s warm, sunny and perfect for a day for the pool. You grab your towel and sunscreen and make a beeline for your backyard. However, you stop in your tracks when you get outside. The pool water is an unseemly shade of green. You can’t even see your pool finish under its murky depths. Hopefully, this has never happened to you before, but, unfortunately, it’s easy for pool water to turn green.

So what can do to stop your pool from turning green? We’ve got you covered.


What Causes a Green Pool?

That cloudy, green water comes from a buildup of algae. These organisms multiply fast under the right conditions: out-of-balance water, warm temperatures, sunlight, stagnate water, and the presence of carbon dioxide, nitrates, and phosphates. In extreme cases, a pool can turn from a clear blue to a cloudy yellow/green pond seemingly overnight.

Not only does the green water look unappealing to swim in — it can be dangerous too. Swimmers risk catching eye, ear and skin infections, as well as digestive illnesses.


Out-of-Balance Water
The leading cause of a green pool is improper water balance. Lack of sufficient chlorine can lead to the perfect breeding ground for algae. The proper pH allows the chlorine to work more efficiently. The correct total alkalinity and calcium hardness levels preserve the interior finish and equipment. The ideal level of cyanuric acid (30-50 ppm)helps keep the sun from depleting the chlorine. A healthy water balance can be easily upset by an influx of swimmers, sweat, sunscreen, rain and debris which alter the water balance significantly.


Wind can blow debris into your pool, which will deplete the free chlorine. Water evaporation in the warmer months will create the need for refilling the pool often, which will change the pool water balance. Frequent water testing is required to assure the free chlorine and the pH is at a good level for safe swimming and to keep algae from forming. Rain can also “wash” debris from the atmosphere into the pool that will cause algae bloom.


Poor Circulation and Lack of Brushing
A lack of proper water circulation/filtration can lead to algae forming on the pool surface and between tiles.. A clogged or dirty filter can prevent water circulation and filtration, making it easier for algae to cling to the pool finish. Frequent backwashing or cleaning of the filter will help prohibit algae. Weekly brushing will clean the pool finish so algae cannot start growing.

Another way to preemptively stop algae from growing in your pool is to increase water circulation with a pool fountain or water bowl. PTI® offers hammered copper or cast stone pool water bowls in multiple shapes. Additionally, pool fountains add a touch of elegance to your poolscape.


How to Go Blue Again

If you wake up one day and discover your pool has turned green, don’t panic. Restoring your pool water back to clear requires just a few steps. Only in extreme cases would you need to drain the pool. For most cases, all you need is the right chemicals and a pool brush to scrub the algae off your pool finish.

Here is some helpful information for chlorine and salt pools:


Acceptable Ongoing Maintenance Range After 28 Days (PPM = Parts Per Million)

    • pH: 7.2 -7.6
    • Total Alkalinity: 70 – 100 PPM
    • Calcium Hardness: 150 – 300 PPM
    • Total Dissolved Solids: 400 – 800 PPM
    • Chlorine: 1 – 3 PPM
    • CYA, Cyanuric Acid: 20 – 30 PPM
    • Langelier Saturation Index Range: Between -0.3 and 0.3


Acceptable Ongoing Maintenance Range After 28 Days (PPM = Parts Per Million)

    • pH: 7.2 -7.6
    • Total Alkalinity: 80 – 120 PPM
    • Calcium Hardness: 150 – 250 PPM
    • Total Dissolved Solids: 2900 – 3900 PPM
    • Chlorine: 1 – 3 PPM
    • CYA, Cyanuric Acid: 30 – 80 PPM
    • Langelier Saturation Index Range: Between -0.3 and 0.3


Additional Tips

  • If any of the levels are outside of the ideal range, make adjustments. This could mean draining some water out of the pool if the calcium hardness and cyanuric acid are too high. Brush the algae from the walls while draining. Refill the pool & retest the water.
  • Lower the pH between 7.2 – 7.6.
  • Check the filtration system to make sure there is no blockage or buildup on the filter.
  • Scrub the walls of the pool with a pool brush before adding chlorine.
  • Add chlorine to raise the chlorine level to 5.0 ppm. Brush as you add dissolved granular or diluted liquid chlorine to the pool. Brush again when it is all added to the pool and run the filter for 24 hours. Check the filter after 6-8 hours to determine if cleaning or backwashing the filter is necessary.
  • After 24 hours, retest the free and total chlorine as well as the pH. If the total chlorine is higher than the free chlorine, repeat step 5. Continue to repeat until free chlorine and total chlorine test the same.
  • Clean/backwash the filter often.
  • Remove the dead algae left behind by vacuuming.
  • Run the filter until the algae is gone.
  • Finally, test the pool water parameters again and confirm they are in the normal range.
  • Additional treatments such as an algaecide or phosphate remover can be used once the chlorine level is established and the algae is removed.


Not The Right Shade of Blue?

Even if your pool water is healthy and free of algae, the color of the pool will vary in different sunlight, cloudy skies, night reflections and water depth. The pool water can be enhanced by one of the many varieties of shades of color offered by Pebble Technology International® pool finishes so you can choose the ideal hue for you. Discover your perfect shade here.

If you’re ready to make your pool water color stand out with a new pool finish or accent the sound of the water circulating and style of your pool with a pool fountain, contact us. Our experts will work with you to make your pool the best it can be.           

aerial shot of light blue pool
Pictured: Almar Jackson, PebbleTec – Sky Blue

Pictured: Regal Pools, PebbleSheen – Prism Blue