I haven’t had a true crash (knock on wood), but almost did. When I rescaped, I must have put a lot of nitrogenous crap into the water, which got all my corals looking iffy. The stress caused my Aussie torch to go down with bjd. This was months ago and I still see some effects, but it is mostly back to normal now. So not a true crash, but seemed like it was on the brink of it.