What items are needed for Auto Water change?

[Bigwrasse]

I have a Apex, and a mixing station and I know I need a Dos pump but what other items such as sensors do I need to automate my water changes?

 

[AB Corals]

I just have a apex + DOS. I have one line in a saltwater container with a heater in it + pump to mix it, and one line runs to a drain in my basement. Very simple

 

[Silent]

You might check this out.