I know it's already been suggested that corals, especially SPS, want consistency.
This is true, but when you think about it the main way of doing this is through the proper use of your equipment.
So I would recommend that, when feasable have back ups for your equipment.
Furthermore, and this is important, never assume that because your doser, skimmer, pump etc was running yesterday it is working today or will work tomorrow.
Check daily. Your equipment may have certain indicaters.
For example, you may be familiar with wave patterns a particular pump makes. If you don't see it, it could mean your pump isn't running.
Just last night, the aerator in my Protein Skimmer stopped running.
This could have went undetected if not for the fact that I was familiar with the noise the aerator makes and when I didn't hear it I knew there was trouble. It turned it was clogged with debris and everything is fine now.
The point is it has been my experience that undetected equipment failures usually will cause things to go south.
When all your equipment is running as they should, your corals will thank you, by thriving.