We strongly recommend an electric air pump. True, a foot pump will work for most inflatable pools, and some are small enough to be blown up with the power of your own lungs. However, electric air pumps are more efficient and less time-consuming.
This is a worthwhile investment, and it’s not too difficult to find affordable options at department or camping supply stores. Your feet and lungs will thank you, as will your kids because most electric pumps will inflate a kiddie pool in just a couple of minutes.