stress it temporarily and hence the recession
That's the thing - it'll stress it, but it shouldn't recede just because of the dip.
It is just additional stress to an already stressed coral that was about to be even more stressed when introduced to a new environment.
Like most coral when there is low light and flow, especially with Euphyllia, there is bound to be recession whereas too much flow will cause tissue damage and too much light tissue burn or bleaching.
Too low - Not overnight, not even in 2 or 3 days.
Not with Acros, Montis, nor Euphyllias.
Too high - definitely.
As long as he is as advised bringing the intensity up gradually, that risk will be reduced.
That's always true, and I did mention it'll eventually need to be moved to higher PAR area.
I did not mention that it needs to be gradually introduced, true. but it also wasn't the matter we were discussing.
We can always bring tips for later care, but it's a bonus - not a requirement, nor a bad thing not to mention every general caring step down the road when it isn't the main, and urgent subject.
nd when you state light or flow doesnt matter- it is essential for this type of coral.
You're taking my words out of context.
With this coral acclimated over an hour, I don't believe temp or salinity would shock it this quickly.
Temperature damage can also be done by putting a coral in 30 C degrees for 10 mere minutes, or 20 C degrees for an hour. No matter how slow you'll drip acclimate it later on, it is bound to show signs of stress and may recede.
For a 2 hour long ride back home, in the winter, maybe under snow. who knows what temperatures the coral have been through.
And as far as salinity goes, you'll be surprised but some people not realize their salinity is way off due to a calibration error. The corals that are already in the system slowly acclimated to it over weeks, sometimes months, however for a new, stressed coral it can be harsh.