What do you use DOS for besides 2 part Ca and Alk?

[FishPersonFL]

I want to get DOS for aquapower. But then I have another pump open to use. I was going to look into sometime doing auto water changes, but I'm thinking I'd need both pumps for that. What do YOU use the dosing pumps for if not water changes (unless just one will work) and if not for two part Ca and Alk? I have a ca reactor already. My alk, Ca, Mg, is totally fine always. And monitored / controlled by trident.
I have an auto top off already for my evap water -- tunze. I guess I can use the other pump as a back up for that.
ALSO is a new DOS coming out soon? I dont want to get one just to have it outdated in a few months. I dont know when current one was introduced.

TIA!

 

[blaxsun]

Some use it for AWC (and yes, you do need 2 free pumps if you want to completely automate it), some also use it for ATO, other supplements, etc.