Here is a diagram of how I plan to lay the plumbing out.
Any suggestions, changes or advice would be appreciated.
Any suggestions, changes or advice would be appreciated.

SkimmersWhich valve are you referring too?
Great video!
I read that when the pump is not running, chlorine gas could go back into the heater causing damage. (Reason for check valve at heater)You do not need the check valve after the heater.
You do need a check valve on the spa return if the spa water level will be higher than the pool water level.
A make up valve would basically go between where you have the flow switch and into a Tee where you have the spa return. So when in pool mode, you could have some flow bypass the return 3-way.
Not a plumbing expert, but since you only want the heater for the spa, would you consider splitting your pool and spa return before your heater? You would need a bypass line to keep some water going to the spa in pool mode.
Just a thought -
Simple solution which will save you money is to just do a self-install so you don't have a warranty![]()
Sounds like it is designed to use 2 pumps (Recirc pump & deep heat returns ... this would be the one in your current drawings) and (therapy pump & jets ... this would only run the jets). Although you might be able to creatively combine them.
I’m going to go against Jason here. Install the check valve as you have pictured downstream of your heater, upstream of your SWCG. It’s needed.
It isnt really needed, but it’s needed.