I have a question about the "salt mix tank"... are you planning on using that tank as your tank top-off or as an R/O resevoir to top off?
the salt mix tank is only for mixing then puming into the sump for WC
I've seen setups that have large salt mix tanks for water changes, but never directly plumbed to the main tank. You run a risk of dumping too much salt water in to your tank... that would be bad.
I would just leave it as an R/O top off instead... or like in my setup, I mix Kalkwasser with my R/O and replace my evaporation that way.
If you want to have a salt mix tank, I would have a seperate container for water changes whenever needed and not have it plumbed directly to the tank.
The salt mix tank only pumps to the sump
Not a bad plan, except the baffles you show between the area marked sump and the skimmer should be between the skimmer and the return pump.
These baffles form a bubble trap to keep the pump from sucking up the micro-bubbles that the skimmer will produce.
ok got it , will make the changes needed ,thanks