You can put the sand in the tank first, then run the already mixed salt solution onto a dinner plate in the tank, to disperse the water evenly, and thus less disturbance of the sand.
Sorry I have not been back in the thread till now. I have had to put this project on hold due to a pretty important thing going on right now. I truly do appreciate everyone for all the advise and it has helped tremendously.
This is all very useful info! I just bought a Prostar 150 and am getting ready to start filling it with RO/DI water and then mix the salt in, then put in the dry rock and then sand. Super stoked! I am so glad I found this Forum!