Why do we need a spa cover? 1) Keep out debris. Keeping leaves, rain and debris out of the spa water is important. This helps the water filters and chemicals do their job keeping the water clear and ready for you next use. 2) Insulate. This is the second most important reason for having a cover. Since you want to jump in your spa whenever the mood or opportunity hits you.
The objective is to keep the spa water warm while using the least amount of power to do so. If your spa cover insulates well that saves you money on your power bill. 3) Easy access to the spa.
If your spa cover keeps out the leaves and insulates the water but you have to wrestle it every time you want to get into the spa then it isn't worth much. In my many years in the spa cover business I have discovered the number one reason people quit using their spa is this one thing, ease of use. If your cover gets heavy and it just becomes too much of a struggle to get in to use the spa you will use it less and less.
You'll sell it or give it away to and say these words as it leaves, "It works fine, it just needs a new cover." Would you give away your car because it needs new tires? If you purchased your spa new it cost about as much as a small car. A note on gazebos, tea houses, obstacles, plantings and privacy fences. These quaint little buildings are fine but they don't belong on your spa. If you went to the fair and bought one as part of a package with your spa, I'm sorry. Do yourself a favor.
Take it off your spa and put it somewhere else in your yard. Use your spa like a spa and let the other be. pretty somewhere else. If you want to use your spa for years to come it has to be easy to get into and any obstruction to that must be avoided. Now that we have defined the purpose of a spa cover let's look at what is currently available to meet those needs. Aluminum covers are rigid and strong enough to handle a snow load and when properly secured they will keep the rain running off and the debris out.
Unfortunately the offer little in the way of insulation. If your spa is seven or eight feet square a rigid aluminum cover could be difficult to manage. I have heard of rigid foam covers being made airborne by the wind and doing serious damage to whatever it slams into. If an aluminum cover were to go flying I can only imagine the damage would be even worse.
Rolling covers are rigid and strong, they make a nice flat surface that can serve as a place to walk or a handy place to stack stuff. They can make it easy to get off and on. The rolling cover does keep out most of the debris but not as good at keeping the rain out or the heat in.
Walk on spa covers are stronger than the typical rigid foam cover. They usually are exactly the same as a rigid foam cover just with added reinforcement to stand up to a little more weight. So they insulate as well as the typical rigid foam cover. They do serve to keep rain and debris out well. The disadvantages are that with the extra strength comes added weight which makes it more difficult to use.
Also since they still use foam eventually that foam will saturate which will make it even heavier. Amazingly, given enough wind they still fly. If one of these covers takes off it will most definitely cause damage. An inexpensive cover is a tarp style spa cover. It will come with a separate thing you inflate and put under it to make the rain and debris out of your spa.
It claims to be easier to handle than an insulating cover so it fails in that area. On the plus side it probably will never fly away or get heavy and break. If the inflatable portion fails it could probably be replaced with a big inner tube. If you want cheap then this would be a good option but if keeping the power bill down (insulation) is important than I'd skip it. Now we get to the insulating spa covers. The first and most readily recognized cover is the rigid foam cover.
This is the type your spa probably came with when it was new. Basically it does a fair job keeping the stuff you don't want out of the spa. Because it has foam inside it does offer more insulation than most of the covers we have covered to this point. But the foam insulation is attempting to keep the water warm without ever coming in contact with it.
Since the little insulation it does offer is dependent on the little air spaces in the foam, once those spaces are filled with moisture the spa cover has roughly the same insulation value as a wet piece of plywood. Your spa has to work harder to keep the water warm. When you finally throw your back out lifting it you went back in to the spa dealer and mentioned it got heavy. He promptly sold you another cover and a bar lifter system to go with it. It worked great until that next cover got saturated.
Oddly enough even a saturated foam cover will still fly in the wind. I have heard of people finding their cover half a mile away after a wind storm. I have people using huge blocks of concrete on their spa covers to hold them down.
Once again if you have to move a stack of bricks to get into your spa I am willing to bet you are not using it very often. The other option is the air filled spa cover. This cover style uses air to insulate like the foam cover but in air chambers rather than rigid foam. The bottom of the spa cover rests right on the water. This cuts down dramatically on heat loss due to evaporation and condensation, and since it insulates starting right at the water surface it does a better job keeping the water warm while using less energy. Using the water for support the spa cover is not trying to make a bridge over the spa so no amount of snow load is going to crush it.
These spa covers have been around for years and are used in places that get world record snowfall (Yes, even the alps) and I have yet to hear of even one being crushed by snow. Since there is no rigid foam to saturate or break they tend to have a useful life much greater than the typical spa cover. Because it has a natural dome shape the air filled cover does a great job of shedding the rain and debris. The air filled spa cover stays put even in the strongest wind storm because there is no rigid wing like surface to create lift.
Even in places that get tremendous winds (yes even Kansas) these covers won't blow away. If you are tired of replacing your spa cover every couple of years and you plan on owning and using your spa for years to come I would strongly urge you to at lease check out this style of cover.
We custom build spa covers that don't break or get heavy. http://www.SpaCap.com