When many spa owners look back, they find that over 90% of the time there is only one or two people using the spa at a time. Your spa should seat four, but not be so large that it impossible for it to be energy efficient on 110 volts. Larger “party” spas require larger pumps and very expensive 220 volt installations. Buy a spa that is the right size for you, not the whole neighborhood. Make sure the height is at least 32 inches and staying under 300 gallons is a good idea.