How Long Does it Take a Solar Cover to Heat a Pool?


We all want our swimming pool water to feel comfortable and enjoyable.  Most people don’t like swimming in super cold water.  One way to help heat your swimming pool water is with a solar cover, also known as a solar blanket.  

What is a Solar Cover?

 A solar cover is a large piece of vinyl, polyethylene, or polypropylene that almost looks like the bubble wrap one would find in a package.  They come in a variety of sizes, colors, and are either rectangular or round.  They are specifically designed for a pool, in-ground or above ground (or even a spa) to naturally heat the water.  This is accomplished through solar rays that come from the sunshine.  They come in different millimeters, which usually determines not only the quality, but the length of the warranty.

 Because they are made of such a thick plastic material with UV inhibitors  they are effective in areas mostly in areas with a dry and/or windy climate.  You put your solar cover over your swimming pool and it kind of floats on the surface.  This not only helps keep debris out, but can help trap existing heat in, while absorbing additional heat from the sun.

How Quickly Will a Solar Cover Heat my Swimming Pool?

According to the experts, a fully covered pool will heat between 10-15 degrees in about 6 hours.  There is mixed information out there.  Some experts say that you will get 7-10 degrees with three consecutive days of sun.  I believe a lot of this depends on different factors.  Things like the thickness of your cover, the ambient temperature outside,  how much direct sunlight your swimming pool gets and whether or not you are pairing the solar cover with a swimming pool heater.

A Must with a Swimming Pool Heater

In my opinion, a solar cover is a MUST if you own a swimming pool heater.  This is because you lose SO much heat off of the surface of the water. Somewhere around 5 degrees a night.  Sure, some of the heat gets absorbed into the swimming pool’s surface, and some condensates, but the majority of the heat is lost from evaporation. 

You already spent thousands on the pool heater itself and paid for the gas to run it…why would you want any of that expensive heat to unnecessarily escape?  When a customer purchases a heater from me I typically have them grab a solar blanket as well.  I can’t in good conscience not make this crucial recommendation. 

Should I Cover My Entire Pool?

There are 2 answers for this question.  In order to get the maximum heating benefit from our solar cover, it is advisable to cover the entire swimming pool.  This also puts you at a bit more of a risk for algae growth if you do not properly take care of your swimming pool water. This means circulation, brushing and water chemistry.  If these are things you struggle with, you may want to only cover 80-90% of the swimming pool.

Can I Cut My Solar Cover?

Absolutely.  In fact, the likelihood that you won’t need to cut it to fit your pool is slim.  You have 2 options when cutting a solar cover.  You can cut it to best fit the shape of your pool, leaving it as one large piece.  The other option is to cut it into manageable pieces for easier removal and placement.  It will not void the warranty to cut your pool cover.

Pool cover warranties cover the workmanship of the cover.  This means the layers of vinyl separating.. It does NOT cover the bubbles falling off as this is typically caused by improper water chemistry, age of the cover or improper storage.

What Size Cover Should I Get?

Regardless of the shape of your swimming pool, you will want to measure the longest part and the widest part.  Then using those measurements, go a tiny bit larger.  Remember, we are going to be cutting our pool cover to fit.  Some typical solar cover sizes are 12x24’, 15 x 30’, 16 x 32’, 18 x36’ and 20 x 40’.  This doesn’t mean there are not other options out there.

All in all, a solar cover is a great way to help your swimming pool water get, and stay, warmer.  They are not very expensive and are available at nearly every swimming pool supply store as well as online.  See you poolside!

Want to know how to heat your pool in an efficient and cost-effective way? Learn here. Is your pool heat pump not working? Here are some solutions.