A friend is giving me Her hot tub. I went to look it over, and here's what I saw.
A Blower.
A Heater
A Pump.

There are 2 lines coming out from under the deck (Not counting the blower line) From there it seems to go everywhere. Im no idiot, but I can't seem to make sense of the piping paths. Is there a generallly accepted order I should be plumbing the equipment in?

T.I.A., Spike.

2 lines coming from under the deck...
those are your pump suction, and jets output.

Suction goes to the pump input, then thru the filter/heater, then out to the jets.

A lot of these older boat tubs will drive you nuts depending on how nutty the previous installer/system designer was.

Indeed. Whoever put this thing in went nuts with the pipe. I'm glad I get to start from scratch. Thanks for you're help!