What are some of the basic considerations of designing a well operating spa? I read the small section in Hydraulics: have you lost your head, but there wasn't much there beyond pipe sizing, 2.5'' vs 3'', and number of jets factoring into head calculations. I am aware of the severe importance of looping returns in spas.
However, I am unsure of how to decide how many jets to put in the spa. My parents' spillover spa only has 4 jets in a 6' circular spa, and it seems inadequate to me. My setup will be a 7-8' octagonal spillover spa into a 17x35 rectangular pool. The spa will have a dual main drain setup. The pump will be a hayward variable speed.
I am currently leaning towards 6-8 jets, but am unsure of figuring out if there is an optimal number of/distance between jets, or if it is mostly personal preference? Would 3/8'' be better than 7/16'' jets? What other factors do i need to take into consideration? I'm located near Tampa, FL, so no winterizing of the spa/pool will be necessary.
I have read on here that a lot of pool builders screw up spas, and I do not want to add to that statistic.