Doesn't your SWCG nearly guarantee that?
Yes, which is why I joked I don't need one for the day-to-day laziness, my SWG covers that. And I set up my automation (acid, too) just so that I
could leave, but I haven't tried it for more than a few days,
yet (geez, I gotta get outta the house!). But "
nearly guarantee" are the key words. I know I'll be, uh, anxious about its reliability when I go for a week or more. I have a pool cam to cover water loss and algae outbreak, so that's my backup. But another layer of redundancy, even for just measuring FC if not dosing (pH, too), would be nice to have. I've just learned my future might hold some extended trips, so I'll be putting what I have in place to the test...
I have a fairly stable environment, but I do get temp swings and the occasional dead animal. Either or both together could trash the FC. And of course the gopher will fall in an hour after I leave, so that he can stew the entire time, as per Murphy's Law.