Acclimating newly arrived seahorses properly after their transoceanic, cross-country journey is absolutely vital. It's not like acclimating the new specimens you bring home after a quick trip back from your local fish store. The long distances and prolonged transit times involved make proper care of the new arrivals once they finally reach you a far more urgent matter. The reason for this is that all the while the seahorses are en route, they are excreting wastes and respiring in the dark shipping box -- consuming oxygen (O2) and giving off carbon dioxide (CO2). That means two things: deadly ammonia is steadily building up in the shipping bag and the pH is steadily dropping, making the water more acidic.
This downward pH shift is actually helpful in that ammonia is less toxic at low pH and becomes much more toxic at higher pH. This is because ammonia exists in water in equilibrium between two different forms -- a nontoxic ionized form usually referred to as ammonium (NH4+) and an un-ionized form (NH3), which is highly toxic. Ammonium (NH4+) is completely harmless to fishes since the ionized ammonia molecule cannot cross the cell membrane and enter their cells. Note that only difference between harmless NH4+ and deadly NH3 is the addition of a hydrogen ion (H+), which converts toxic ammonia to nontoxic ammonium. At low pH, the extra hydrogen ions (H+) of acidic water are readily available to attach to the ammonia molecule, converting most of the ammonia to ammonium: NH3 + H+ ---> NH4+. But at high pH, under alkaline conditions, exactly the opposite occurs. At high pH, the abundance of hydroxide ions (OH-) in alkaline water strips the extra hydrogen ion (H+) away from ammonium, rapidly converting most of it to deadly ammonia: OH- + NH4+ ---> NH3 + H20. In other words, the higher (more alkaline) the pH, the more ammonia is present in the dangerous un-ionized form (NH3), which easily crosses cell membranes and enters the body.
This should make it easier to understand exactly what is happening in the shipping bag. As the seahorses breathe, consuming O2 and giving off CO2, the pH of the water drops and more of the ammonia (NH3) they produce is assimilated into harmless ammonium (NH4+). So the decrease in pH that occurs during long-distance shipping is actually protecting the new arrivals somewhat -- until we open the shipping bag! Once the shipping bag is opened, CO2 begins offgassing from the bag water and fresh O2 begins entering the water, and as the pH begins to rise in response and return to normal, the ammonia in the water becomes increasingly poisonous. And when we begin to add alkaline water with a pH of 8.0-8.4 from the main tank to the shipping bag, we are accelerating the pH shift and converting ever more of the ammonium (NH4+) to deadly ammonia (NH3). The suddenly high concentration of ammonia in the water quickly diffuses into the seahorse's cells, and acclimating the new arrivals becomes a race against ammonia poisoning just that quickly.
Acclimating farm-raised seahorses properly is therefore the art of achieving the proper balance between two conflicting needs: the need to get them out of the toxic shipping water as quickly as possible and the need to allow them to adjust to tank conditions as gradually as is practical. Drip acclimating the seahorses over a period of hours would expose them to dangerous ammonia levels for an extended period with harmful results, and adding an airline or otherwise aerating the seahorses in the shipping bag while they are acclimating, would likewise increase the levels of ammonia they were exposed to. In the case of Ocean Rider seahorses, which may have been in transit for 24-48 hours, the first of these needs – to get the seahorses out of the noxious water in the shipping bag as soon as possible – should be your first priority! If all goes well, it's therefore important for the acclimation process to take no more than 10 minutes before your Ocean Riders are released into the main tank.
Whereas drip acclimating is definitely the way to go when you bring home delicate invertebrates that are highly sensitive to water quality from your LFS, such as live corals, starfish, and decorative shrimp, it would actually be quite counterproductive for seahorses that have just arrived all the way from Hawaii.
