How to do a reef tank water change

[Milad]

My water change steps for with my new fish room which is half complete is going to be the following:

Flip a switch to stop water flowing into water change reservoir
Flip a switch to dump reservoir
Dump premade amount of salt into resrvoir
Come back next day and flip switch to let water flow back into reservoir

The only thing I can come up with to make it easier is somehow automate the adding of the salt but I seriously dont have any good ideas for it without making it too complicated and finicky