Black covers are opaque, allowing no light or UV rays to pass through the cover. The opaque quality and black color do allow for very fast and easy heat absorption, heating your pool quickly. However, this comes at a cost: black solar covers are typically the first to break down from wear and tear.
A swimming pool tarp, for example, that's black on both sides is like a giant solar panel. Because a black tarp on a swimming pool's water surface traps solar heat energy, it will eventually turn cool, refreshing pool water into a tepid, warm bath.
Covering a pool when it is not in use is the single most effective means of reducing pool heating costs. Savings of 50%–70% are possible. Pool covers on indoor pools not only can reduce evaporation but also the need to ventilate indoor air and replace it with unconditioned outdoor air.
"By putting black bin bags on top it attracts the sun and it warms it up very quickly. Within about 45 minutes the water is warm and stays warm all day in the sun."
Solar Heaters
The next cheapest way to heat a pool is through a solar heater. The cost of running a solar pool heater is essentially free, aside from occasional maintenance. The difference is that a solar heater is a lot more expensive to install – often even more expensive than a conventional heater.
Air bubbles in the pool cover act as an insulator in a similar way that your thermos would keep water warm. A pool cover will, therefore, keep your pool water warmer for longer.
How many degrees will a solar cover heat a pool? On average, a fully covered pool can gain between 10-15 degrees on a sunny day within about 6 hours.
When the "bubble paper" pool cover absorbs the suns rays it gradually heats the water in the pool while the cool pool water keeps the solar cover cool. The pool cover will usually heat the pool water up by one degree per day.
So while a solar cover won't actually 'turn your pool green', it will warm your water by up to 8 degrees, so if the other conditions are right, adding a solar cover can easily accelerate algae growth, very rapidly. You need to get the water balance in your pool right before putting the cover back on.
You should never leave your pool heater on overnight. Doing so is not efficient and will cost you more than it would if you just turned the pool heater off. While many of us know that heating a pool can take up to several hours, running it overnight defeats the purpose of heating it at all.
A pool that is uncovered can lose up to 5 degrees F overnight; a good cover can cut that loss by half. Used at night or whenever your pool is not in use, the pool cover can help save fuel costs by cutting heat loss regardless of the type of heating you utilize.
We have found that turning the heater off at night allows the water to cool rapidly. The heater then has to burn at a higher rate in the morning to make up the lost heat. The higher you turn the burner the lower the heating efficiency and the greater the heat loss from the exhaust gases.
Conclusion. Solar rings not only keep your pool water warm but also reduce the amount of dirt and debris that might end up in your pool. With solar rings, you won't have to worry about any chemicals or electricity to maintain the temperature of your pool.
You should cover your pool every night for several reasons. First off, a pool cover saves energy and conserves water by decreasing the amount of make-up water. Also, it reduces the consumption of chemicals, and finally, it saves a lot of cleaning time since it keeps the debris out of the pool.
Without a heater it very much depends on the weather. A number of hot sunny days or quite a few cool cloudy days, anything from two days to a month. It also very much depends on how much you want to get in the pool, ie are willing to try the pool at cooler temperatures.
Heat transfer efficiency is higher with higher flow rates. However, you have to look at total efficiency and cost. It may be worth the extra heat loss to run the pump at lower speeds.
Use a gas heater
Gas pool heaters offer the fastest heating of all the options in this post. And that makes sense because just like a grill or oven, a gas heater creates heat by burning gas. But at the same time, they also have the highest monthly operating cost of all pool heating options.
If you want to get as much time as possible out of your pool, however, a heater is a good investment. With a pool heater, you can easily be swimming May through mid-October, giving you a good five months of use out of your pool. That's literally double the amount of time you'd get without one.
A pool heat pump should not be left running all the time. For one, you are wasting electricity by keeping it on when your pool is already warm enough. Also, this will lead to an increase in energy costs month after month.
There are millions of natural gas and propane swimming pool heaters in use across the USA and the world. You would be hard-pressed to find an incident with one of them that has caused them to explode while in use. That's despite the fact that these devices have been in use on swimming pools for several decades now.
Not only will it be tough to keep the heat in your pool on colder nights but you will also spend a fortune trying to heat your swimming pool. So unless you have money to burn, it's best not to run your heater at night on an uncovered swimming pool.
If installing a pool cover over winter, wait until the chlorine level has reduced to between 2-3ppm. Reduce the Chlorine Production Output (CPO on your chlorinator). The pool cover will maintain 90% of the chlorine (produced by your chlorinator) in the pool, as opposed to loosing 70% of chlorine in an uncovered pool.