Depending on the temperature you need your pool to swim, leaving your pool overnight affects your heating costs and the size of your pool’s heater. Naturally, people recommend the normal temperature for your pool water between 78o F and 82o F.
However, keeping your pool at around 78o F would enable you to save cost on energy consumption, but your pool would be too cold for kids and the elderly, so you need to raise it to at least 80o F.
Now, if you want to use the pool the next morning, keeping the pool heater off at night would not be useful as the night weather would rapidly cool down the pool’s temperature, leaving the heater to burn at a higher rate when you want to use the pool.

You may want to get the pool hot in the morning by turning up the heat, but this would only reduce the heating efficiency and increase the heat loss from exhaust gases. You might have been if that “should I leave my pool heat pump on all the time?”. Now, if you want to solve your pool heating challenges, you have to read on.
Is it Better to Run a Pool Pump at Night or Day?

This is a question on many people’s minds because it keeps them confused about the decision to take. However, here are the facts. Running your pool pump at night is an excellent option to choose and even cheaper, but it is not sufficient and may cost the pool owner time and money. It would also aid in the growth of algae because they need heat to grow, which is not the best option.
The best option to take is to run your pool pump within a specific time of the day for a calculated period. So say you want to run the pool in the afternoon, you can run it for at least an hour in the afternoon at a specific temperature of heat and store the energy by covering your pool with a solar blanket afterward.
The only time it is good to run your pump at night is to carry out a major chemical cleanup such as algae treatment.
How Long Does it Take to Heat a Pool?
The required time it takes your pool to heat up depends on several factors such as heat pump size, air temperature, pool size, and material used to heat the pool. However, the overall time it takes a pool to heat up usually lies between 24 to 72 hours, which heats the pool by 20o F.
Heat pump size: the size of your pool determines the size of the heat pump that would successfully heat the pool, so to know the size of the heat pump to install in your pool, you need to calculate the size of the pool.

Air temperature: The air temperature is also another factor, but that depends on whether you’re using an air-source heat pump. If you’re using an air source heat pump, the pump will operate efficiently when the air temperature is higher than 50o F. If the air temperature is below this reading, your heat pump would not be able to capture heat from the air.
Pool Size: The pool’s size is also essential to the heating time because the bigger the pool, the more heating time it consumes.
The material used to heat the pool: Different materials have been developed to reduce the pool heating cost. One of such equipment includes the solar blanket. The solar blanket is efficient in heating pools as it reduces heating time and minimizes evaporation, which is a major cause of the loss of heat from swimming pools.
These are the few factors that affect heating time in a pool; however, you should note that each pool is different, and heating times vary.
Conclusion
It is not advisable to heat your pool at night because of the time and energy it will consume. You’re advised to heat your pool during the day for more efficiency, and if you can, buy a solar blanket to retain the temperature of your pool.