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11 Proven Methods to Cool Your Pool Water Fast

I’m sure you’ll agree that the best thing about having a pool in your backyard is being able to plunge in on a sweltering day and get that immediate, blessed relief from the cold, sparkling water. But what happens if your pool has been in that baking sun all day and the water is lukewarm? There’s no fun in that – it’s not refreshing, and it’s not going to cool you down, so how can you get your pool water cool?

One can use fairly advanced technology such as reverse-cycle heat pumps and solar panels to cool pool water, but it’s also possible to employ simple, inexpensive means, including aerators, evaporative pool coolers, and fountains, to reduce the temperature while the pump is circulating the water.

If you live in a Mediterranean climate as I do, or any area with hot, dry summers, you’ll have experienced your pool water getting steadily warmer until it’s less refreshing than you’d like. It’s also a fact that warmer water is more prone to algae, microbes, and bacteria that thrive at higher temperatures. So let’s look in detail at the best way, in terms of cost and effectiveness, to get that pool cooled down.

How To Cool Pool Water – What’s The Best Method?

There are simple ways to cool water, using fundamental laws of physics, and then a few methods that take advantage of technology and innovation. I’ll detail both mechanical and non-mechanical means of cooling your pool.

Non-Mechanical Cooling Of Pool Water

This is the simplest and probably the least expensive way to reduce water temperature.

  1. Erect A Shade Sail – a well-positioned shade sail that casts a shadow over the pool during the hottest part of the day will definitely reduce the temperature of the water and will also protect the people using the pool from the damaging ultraviolet rays of direct sunlight.
    You can create shade with landscaping and plantings, but in my opinion, this is more aesthetically pleasing than practical. Trees take years to provide shade, and having too many poolside plants will act as a windbreak and prevent cooling breezes from bringing temperatures down.
  2. Choose a white or very light-colored finish for your pool surface. Whether you have a tiled, concrete, or vinyl pool surface, there are heat-reflective options that will resist heat absorption. Dark colors might look appealing but will absorb heat and transmit it to the water. The same rule applies to the pool surround.
  3. Pool covers. Pool covers made from heat-repellent fabric may not reduce the temperature of the water but will prevent it from increasing from exposure to the sun. However, my problem with this solution is that the cover needs to be fitted over the pool during the hottest part of the day – and that’s exactly when you want to swim! If the pool is not being used, it’s a possible method to keep your pool cool.
  4. Adding Ice. This “fix” is often suggested, but I think you should take it with a pinch of salt – it’s been calculated that to bring the water temperature down by 5⁰F in a 10,000-gallon pool will take over 2,000 lbs of ice, and of course, it’s a very temporary solution.

Mechanical Means of Cooling Pool Water

By “mechanical”, I am referring to all the cooling methods that require the water to circulate through the pool pump and filtration system. Many of these methods don’t need additional moving parts, but some use a more sophisticated technology to cool pool water.

  1. Fountains, Wall Jets, and Waterfalls: These three water features serve a dual purpose. Firstly, they add a new visual dimension to any pool, adding to its aesthetic appeal, and the sound of the moving water can also be very pleasing. More importantly, they assist in lowering the pool water temperature by aerating it and increasing the evaporation level.
  2. A Misting System: You may have experienced misting at various outdoor venues such as pavement cafés and even backyard decks, where it’s very effective in cooling the air. Around the pool, by cooling the ambient temperature, the pool water will also lose heat, aided by evaporation.
  3. Pool Chillers: Pool chillers work on the same principle as a refrigerator, using a refrigerant under pressure to remove heat from the pool water before it returns to the pool. Water-cooled chillers are more effective than air-cooled ones, but both are very effective, relatively inexpensive, and can reduce pool water temperature by 10⁰F or more within 8 to 12 hours.
  4. Pool Aerators: Aerators are simple, highly effective devices that work on the same principle as fountains but more energetically. They take water from the return pipe and spray it through a nozzle or a set of nozzles so that it arcs into the air before falling back into the pool. In this way, the water is oxygenated, reducing the temperature and resulting in fewer algae and other pathogens in the water.
    Aerators use a separate pump to create sufficient pressure and can be electrically- or solar-powered.
  5. Heat Exchangers: While typically used to heat swimming pools, a heat exchanger can use cold water from an outside source, which is run through one half of the exchanger while pool water is pumped through the other half, transferring its heat to the cold water in the process.
    The biggest drawback of this method of cooling pool water is the amount of external water used – you would ideally need a river, dam, or lake to draw cold water from, as opposed to expensive municipal water.
  6. Solar Pool Heating Systems: If the ambient air temperature drops sufficiently at night, the solar panels you use to heat the pool water can also be effective in cooling it. By running your filtration system when the air is cooler than the pool water, you’ll successfully lower the water temperature.
  7. Nighttime Circulation: Running your pool pump at night and circulating the pool water in the cool air instead of the hot sun will have a marked effect on the water temperature. Also, removing pool covers at night will allow radiation of heat into the cooler night air.
While learning about how to cool pool water for a better swimming experience, don't forget to also consider pool deck materials that stay cool to maximize comfort during those hot summer days.

Combining Mechanical And Non-Mechanical Methods To Cool Water

I’ve examined all the most common and effective ways to cool your pool water, but it’s impossible to recommend one specific method over another as so much depends on the conditions you must contend with. Is the pool in full sun all day? Is there a steady breeze over the pool area? Is there enough space to erect a pool awning or a shade sail?

An ideal solution may be, for example, using an aerator at night in conjunction with your solar heating panels and having a shade sail to shelter the pool from direct sun during the heat of the day.

Conclusion

There are several ways to keep a pool cool and refreshing during summer, both mechanical and non-mechanical. Each has its pros and cons, and a combination of methods may be the best way to solve the problem of a too-warm pool. Once you have looked at the options I’ve discussed and the cost-effectiveness of each, deciding which one suits your specific needs should be easier – I hope I’ve helped.