6 minute read

Most pool owners buy a cover, throw it on, and assume the job is done.

It isn’t.

A solar pool cover that fits wrong, has the wrong thickness, or gets stored badly isn’t doing much for you. And every day it sits there not doing its job, you’re paying for it in heating costs, chemical top-ups, and water evaporation you never even notice.

This guide covers what matters when it comes to solar pool covers. Not the sales pitch. The real stuff.

What a Solar Cover Does

Let’s start here, because a lot of homeowners are fuzzy on this.

A solar pool cover does three things. It helps naturally heat your pool by trapping heat from the sun during the day and holding it in the water overnight. It dramatically reduces evaporation, which is where most of your water and chemical loss is coming from. And it keeps debris out, which means your filter runs cleaner and your water stays balanced longer.

That’s it. Simple in theory. But the results add up fast.

An uncovered pool can lose up to half an inch of water per day to evaporation in warm weather. That water takes heat with it. It also takes chlorine and other sanitisers, which means you’re constantly topping up chemicals that just disappear into the air. A well-fitted solar cover cuts that evaporation by up to 95 percent.

For a heated pool, that translates directly to your energy bill. Less heat escaping overnight means the heater runs less. Less chemical loss means you buy less product. Across a full swimming season, the savings are real.

The Thickness Question

This is where most people make their first mistake.

Solar covers come in different thicknesses, measured in mils. The most common are 8 mil, 12 mil, and 16 mil. Thicker isn’t just more durable. It also insulates better and traps more heat.

An 8 mil cover is fine if your main goal is just keeping debris out and you live somewhere warm. But if you’re trying to extend your swimming season into cooler months, or if you run a heater and want to see a reduction in your energy costs, you need to go thicker. A 12 or 16 mil cover will hold heat overnight significantly better than a thin one.

The trade-off is weight and price. Thicker covers are heavier to handle and cost more upfront. But if you’re buying a cover purely to save money on heating, a thin cheap cover is false economy. You won’t see the savings you’re expecting.

Fit Matters More Than People Realize

A cover that doesn’t fit isn’t just annoying. It’s ineffective.

Gaps around the edges are where heat escapes, where debris gets in, and where evaporation keeps happening. A cover that’s too small for your pool is essentially decorative. One that’s too large bunches up at the edges and creates pockets where water sits and breeds algae.

The best option is a cover sized specifically for your pool’s shape and dimensions. For standard rectangular pools, this is straightforward. For pools with unusual shapes, freeform edges, or attached spas, a custom fit is worth the investment. Properly fitted swimming pool solar covers eliminate the edge gaps that make a loose cover so much less effective than it should be.

If you’re trimming a cover to fit, take your time and cut conservatively. A little overhang is fine. Leaving large gaps at the corners is not.

The Right Way to Use One

A solar cover only works when it’s on the pool.

That sounds obvious, but plenty of homeowners put the cover on during the day when the sun is warming the water and take it off at night when they’re not using it. That’s backwards. The cover’s most important job is overnight heat retention. Leaving the pool uncovered from 10pm to 7am undoes most of what the sun did during the day.

The habit should be to put the cover on when you’re done swimming for the day, and stays on until someone is about to get in. That’s it. Simple, but it makes a significant difference to how warm the water is in the morning and how much heat your heater must replace.

During extended periods when no one is swimming, leave it on continuously.

Common Mistakes That Kill a Cover Early

Solar covers don’t last forever, but bad habits make them fail much faster than they should.

Folding it wrong. Don’t fold a solar cover flat like a sheet. The bubbles crack along the fold lines. Roll it instead, bubble-side in, onto a reel or a foam noodle. A decent cover reel is worth buying at the same time as the cover.

Leaving it on during chemical treatments. After shocking your pool or adding large doses of chemicals, take the cover off for a few hours. High chlorine levels degrade the cover material from underneath. This is one of the most common reasons covers fail within a couple of seasons.

Storing it in direct sun. When you take the cover off for an extended period, don’t leave it draped over a fence or folded on the deck in full sun. UV exposure when it’s not on the water accelerates degradation fast. Store it rolled, in the shade or in a bag.

Ignoring it until it falls apart. Check your cover periodically. If the material is becoming brittle, if large sections of bubbles have detached, or if there are significant tears, it’s not working properly anymore. A deteriorating cover that looks fine from a distance might be doing almost nothing for you.

When to Replace It

Most solar covers last three to seven years depending on quality, how often the pool is used, and how well the cover is maintained.

The signs it’s time for a new one: the bubbles are detached or collapsed across large areas, the cover has become stiff and brittle, it tears easily when you handle it, or it’s noticeably thinner and lighter than when you bought it. At that point, you’re not retaining heat or reducing evaporation the way you should be. The cover has become a false sense of security.

Replacing it promptly is cheaper than running a heater harder than necessary for a full season.

The Bottom Line

A solar pool cover is one of the highest-return accessories you can buy for a backyard pool. Not because it’s exciting, but because it quietly solves several expensive problems at once.

Get the right thickness for your climate and how you use the pool. Make sure it fits properly. Put it on every night. Store and handle it in a way that doesn’t destroy it prematurely.

Do those four things, and a solar cover will pay for itself within a season or two. Skip them, and you’ll wonder why yours never seemed to make much difference.