A 24-foot diameter pool is the most popular size for a round above ground model, while 15 by 30 feet is a common choice for oval-shaped pools. However, you'll find round sizes everywhere between 8 and 33 feet. Oval pools range up to 21 by 41 feet but can be customized to stretch much longer. Choosing the right size will come down to where you can level your yard and how many swimmers plan to use the pool at a given time.

Swim spas are like hybrid hot tubs and pools. They have the heating and jets of a hot tub, but they’re slightly longer because they’re made for swimming and exercise. A jet provides a continuous current that acts like a water treadmill. You can swim the length of a full-size pool without going anywhere.

When you’re winterizing your pool, you need to drain some of the water to prevent cracking and warping from ice. Nonetheless, you should never drain all of the water. Ideally, you’ll lower the water level to anywhere from four to six inches below the skimmer. This will protect the structural integrity of the walls, help prevent your pool liner from warping, and reduce damage from debris.

Generally, you do not need to drain your pool to convert it to a saltwater system. The main exception is if you have used an antibacterial agent containing polyhexamethylene biguanide to sanitize your pool, as these sanitation products do not mix well with saltwater systems. If this is the case, you will need to start fresh. You can either drain the pool or treat the existing water with a high dose of chlorine to remove the antibacterial agent. If you choose the chlorine treatment, wait several days to allow the chlorine to work before proceeding with the conversion. If you are unsure whether this applies to your pool, consult a pool technician.