There are a lot of possible configurations, so a little difficult to specifically answer the exact plumbing you will need. Here is my mixing station with the parts I used for the mixing station and continuous auto water change.
Salt water mixing station part list
A- Spectrapure Mega MaxCap Performance Plus RODI UNIT
B- Neptune DOS
C- Quick Connect Adapter for DOS Qty: 4
https://www.freshwatersystems.com/products/john-guest-female-adapter-nptf-polypro-1-4-x-1-8-nptf
D- John Guest 1/4” RO Tubing- 500’ spool Qty 1-2 depending on distance
E- 125’ Aquabus Cable (Length due to distance from garage to apex base unit at display)
https://www.usbfirewire.com/parts/rr-apex-xx.html
F- Full Drain Inductor Tank & Stand 110 Gallon. Purchased locally Qty 2
G- 2” Male Pipe Adapter Schedule 80 , Qty 2
H- 2” Spigot to 1” slip reducing bushing, Qty 2
I- 1” Cepex Union Ball Valve, Qty 4
J- Pan World 50PX-X. Pump Qty 1
K- 1” Union Thread x Slip. Qty 2
L- Schedule 80 Reducing Bushing 1” Spigot x 3/4” Female Thread Qty 1
M- 3/4” Male Thread Quick Connect Cam Lever Coupling B Qty 1
N- 3/4” Female Thread Quick Connect Cam Lever Adapter A Qty 1
O- Schedule 80 3/4” Straight Barb Qty 1
P- 1” Bulkhead ABS Slip x Slip Qty 1
Misc- 1" PVC Tubing, Elbow, Tees, 45s. I ran the plumbing along the stem wall and utilized seven 90 degree elbows, two T's, and two 45 degree elbows to get the plumbing down from the stem wall to be in line with the pump.