I think stability, at least in the way that I think most reefers think of it, is largely overrated. And I’d go one step further and say that it’s unnatural. Obviously, wild parameter swings are not good, but it’s been my experience that slight variations in temp, salinity, and alkalinity are healthier, more natural, and overall more beneficial to corals and the inhabitants of our tanks than hardcore stability.
Again, I’m not talking about big, fast parameter swings, but allowing your tank’s temp to vary by a few degrees, or your salinity to vary by a couple ppm, or your alkalinity to swing by +/- 0.3 dkh is overall a benefit to your tank. Corals in the wild experience these changes minute to minute, throughout the day, seasonally, and over decades.
The temp on a reef can vary by several degrees minute to minute, the salinity and alkalinity can change significantly during a rain storm (most corals come from the tropics where it rains a lot, shallow in shore reefs see big swings during storms). Nutrient levels vary on natural reefs, too, though I think most people keep their nutrients well above natural reef levels, so that’s of less relevance to my point.
I have observed that when parameters are kept as stable and static as possible, any tiny change causes a noticeable negative reaction in corals, whereas tanks where parameters are allowed to vary, corals aren’t stressed by minor changes. While I think it’s important to keep parameters within acceptable ranges, I do think that not allowing for some variance is detrimental. Over time it leads to corals that are less hardy and less suitable for average home aquariums.
I think when you’re first starting in the hobby, it’s probably good to aim for stability, because once you’re able to keep things stable, you’re able to allow for some instability in a controlled way. But, overall, and especially for experienced reefers, stability is given way too much importance.
