I would LOVE for my HA system to control my pool. And since upgrading all my old Insteon devices to their newer mesh/RF versions, my system has become near 100% reliable. And that's the rub, the "near" part. Every once in a while my fax machine comes on. I can't find the cause. Probably an intermitent, faulty Insteon outlet device. Or some command has to be repeated before a light will come on: maybe some sort of mesh network interference issue. And far too often, the devices just croak and need to be replaced, in or out of warranty. For faxes and lights, no big deal. But for pool equipment, that has valves that have to turn in sync, or pumps that must turn on and off as programmed, or acid dispensers that can't pump acid into SWGs or they might create poisonous gas, things can't be "near" reliable. Granted, no pool electronics are 100%. It's not possible. They're electronics. But I want to believe my Pentair gear is as close as possible (and it certainly has been more reliable than my HA). Just pointing out something to think through before you put some powerful and potentially dangerous components into the hands of inexpensive HA devices, Apple (or others') software, and/or DIY solutions.
I like Apple, my house is filled with their products. But I'm still remembering the time I called support to complain about my calendar app, which kept losing my appointments and events. Their response? "Well, we designed that for consumer use, not for professional applications." Wha?!? So I can only rely on it to remember things I don't really need to remember? Nice.
HA is in its growing-pains stage. It's awkward, pre-teens years. I'll let it turn on and off my lights (even my pool light). It'll get the keys to the Ferrari when it can pass its driver's license test! I complain often about how slow Pentair and the others are to adopt now-mainstream technologies (HA, WiFi, ethernet, and other non-proprietary solutions, etc), but there's something comforting about the fact that my pool's controller has been doing its thing, in 1000s of pools, in the same way, for a decade or two.
