BTW, I've probably acclimated 50,000 fish in my life and these aren't just damsels, clownfish, and other hardy fish. Many of my animals have been very rare (and expensive) At the store, I buy it in several gallon jugs. When acclimating a shipment, the first thing that goes in the acclimation tub, is Prime. At home, I use it too because you don't know if the fish, anemone, etc went to the bathroom on the drive home. At my store, we fill the top of the bag with Oxygen so there won't be any pH drop while people drive their new purchase home. However, if people buy fish online, doing a slow acclimation drip can ACTUALLY BE DANGEROUS if you don't add Prime (or Amquel). I won't go into too much detail here but I'll try and explain it quickly. When fish respirate, they are just like us. They take in Oxygen and expell Carbon Dioxide (CO2) Ammonium and Ammonia are the same thing depending on the pH of the water. As the fish continues breathing in the bag, more and more CO2 enters the bag. Now, that's a good thing because this excess CO2 drives down the pH which, in turn, converts the very dangerous Ammonia into harmless Ammonium. Here's where it can become dangerous. This fish has been in this bag for the last 24 hours (or more) and probably has gone to the bathroom by now. Once you open that bag, allow the CO2 to offgas and be replaced by Oxygen, the pH will rise again which will convert that harmless Ammonium into very dangerous Ammonia. That's why I believe every serious reefer should have Prime on hand at all times.