Aquarium fish and coral acclimation has two general schools of thought. For one, we’ve always been told that drip acclimation of newly purchased aquarium animals for up to 2 hours was always the best method. While I generally take this route for locally purchased animals, acclimating corals that were purchased online might need to be done a bit differently. As a coral sits in a bag of water, it will release mucus and other things that will degrade the quality of the water in the bag. These byproducts build up to dangerous levels, and when drip acclimating the coral, ammonia for example can become extremely dangerous. For these reasons, a lot of fish stores may not drip acclimate corals.
Years ago when I first saw this, I was actually shocked. The store seemed to be breaking all of the rules for successful reef keeping. However, their explanation and reasoning made sense. Why prolong the coral’s exposure to ammonia? Drip acclimating only dilutes it and at a very slow rate. They felt their best chance of success was to get the corals out of the water they were shipped in and into “clean” water. Keeping their advice in mind, I have tried the “no acclimation” approach on a few corals and found that the corals still survived and even thrived in their new environment. I do not know if these non-acclimated corals did better or worse than corals properly acclimated, but they certainly did not die. I want to end by saying that I do not promote taking a route of non-acclimation. I still drip acclimate everything for at least two hours, following this by a brief iodine dip for corals.