.023-.025 is still not that bad of a swing as long as its spread out as long as possible. There are several species of corals that would tolerate that shift in a one or two day period, but some testy species such as some xenias may not appreciate it and shrivel up. I have inadvertently caused xenia death by increasing salinity from .022-.027 in one day, so I know at least that much of a shift is hard on marine inhabitants. I dont usually do this to my tanks, theres a longer story of why it happened that time. When that did happen, though, the xenia were the only ones to die. SPS and LPS made it just fine but I wont be doing that again.
Its hard to state absolutes on what salinity shift is detrimental to our reefs, we stock with so many kinds of inverts and fish, each with varying levels of tolerance, so its kind of a roulette game until you see someone shrivel up--then you know you have lost. Id say a shift of .001-.002 in a one or two day period is okay, but at that rate you could get stressful if you allow it to go another day without topoff for whatever reason.
imo Brandon