"New to me" spa questions

[CuckooChris]

Hello, getting ready to hook up an older spa that I got from my neighbor and trying to get everything in order, but I'm stuck on what size breaker to use. It was connected to a 50A, but I think I can use a 40A. The pump says it pulls 11.4A on high and I have ordered a 4.5kw heating element which should pull about 19A. So I'm at 30.4A plus the control box, light and ozonator. 80% of 40 is 32, so that would be my limit. Do you think I'm too close to use a 40A? Also, what would be the proper way to run the line. I have a brick wall next to the spa. Can I run the conduit over top of the wall or do I need to go through the wall? Thank you

 

[RDspaguy]

I have never heard of a 4.5kw heater. They are usually 5.5 or 4.0. 5.5 draws 24 amps, 4.0 draws 17 amps.
Many spas have a low amp setting which disables the heater when pump is on high speed. I would recommend using the 50 amp. Gfci disconnects are around $100 at home depot.
If in conduit, the wire can be ran over the wall.