How early in the year can you use the pool in SoCal?

[Ashley Kwiecinski]

We just bought our first home in San Diego, CA last month and it has an unheated in ground pool. My husband and I are fairly inexperienced when it comes to pools in California and I was wondering if any one knows on average when during the year the pool water begins to be warm enough to use. Our pool is between 20,000 and 24,000 gallons. I had originally been hoping to be able to use it for my daughter's birthday party at the end of April but a fellow pool owner out here said that was unlikely.

Although we will probably eventually install a solar heating system for the pool that won't be in the near future. Assuming that the end of April is still too early, is there anything we can do to help us in being able to use the pool any sooner? Would a solar cover make a difference?

Thanks for any input!

 

[chem geek]

Welcome to TFP!

With no solar heating and if you aren't using a pool cover then the water temperature will be roughly the average of the day/night temperature because the rise in temperature from sunlight is roughly counteracted by the cooling from evaporation of the water at usual humidity levels in San Diego. From this link the average of the day/night temperature rounded up is the following:

Jan . Feb . Mar . Apr . May . Jun . Jul . Aug . Sep . Oct . Nov . Dec
57 ... 58 ... 60 .. 62 ... 64 ... 67 . 70 .. 72 ... 71 ... 67 .. 62 ... 57

So you can see that if you don't use a solar cover the water won't be warm. A bubble-type solar cover should increase the water temperature by around 10-15ºF putting your June and October temperatures into the 77-83ºF range while your August peak could be in the 82-87ºF range. A solar system would extend your season since combined with a solar cover it could add 20-25ºF to the pool (it will shut off to prevent it getting too warm) so would extend the season perhaps from March to October IF you have sun in those months (if it's overcast then you won't get as much heating).

As for swimming in April, that depends not only on whether you use a solar cover (temp perhaps in the 72-77ºF range) but also what temperature is the minimum for swimming which is personal taste. Pools used in competitive swimming are typically 78ºF. However, that is too cold for some people (though kids don't seem to mind colder water as much).

 

[Casey]

It all comes down to whether or not you or others enjoy a brisk swim. Me... not so much! I've seen my kids swim in 70 water.

Welcome to TFP!

 

[Ashley Kwiecinski]

Thank you both for your replies, this was actually very helpful! We need to buy a pool cover anyways, so we'll buy a solar one and then when we can afford to put in the solar heating we'll *hopefully* do that too. My husband and I are actually from Michigan originally, so I don't think brisk swims will be a problem for us. A pool party just isn't a pool party if no one else is in the pool though! Thanks again, this was really good information!

 

[Richard320]

I don't find the pool swimmable until about May. But I don't bother with a cover, either. Nor do I have solar panels.

 

[BoDarville]

It all comes down to whether or not you or others enjoy a brisk swim.

^^This is really the determining factor.

I will tolerate water temperatures of 65°F for lap swimming. Here in North Texas, that has occurred in my pool as early as mid-March while in other years it has occurred in early to mid-April. I would suggest getting a good instant-read digital thermometer (I use a ThermoPop from Thermoworks ~ $30 but they occasionally run specials where you can get it for less than that). I insert the probe as deep as it will go while keeping the display (and about the top half-inch of the probe) above water. Within a few seconds, you will have the temperature reading. Assuming you have some idea of the water temperature you can tolerate, you will know when the pool has reached that temperature.

If you happen to have a gas heater, you can use it to raise the temperature a bit prior to a planned event. While it is expensive to heat a pool on an ongoing basis, gas heaters are good for "event heating" as they will raise the temperature more quickly vs. other types of heaters.