How to Acclimate Corals

Acclimating corals to a new tank safely involves introducing them to your system’s water slowly.  This prevents them from being shocked by a difference in temperature.  The first step in this process is to float the corals in your

home fish tank with hose attached to drip tank water slowly into smaller container

Drip Acclimation

tank, keeping them in the bags they came in.  This should be done for at least 30 minutes.  Some people think this is unnecessary, but there can be a significant difference in temperature, alkalinity, and many other water parameters between the water in the bag the coral was packaged in and the water in your tank, so it is very important to complete this step.  Second, place the corals with the water from their bags into a small container and add water from your system slowly.  The easiest way to do this is typically to attach a pinched siphon hose to your tank and allow the water to drip into the corals’ container.  Once the volume of water in the container doubles, test its gravity (amount of salt compared to water), pH, and temperature.  If the values are not identical to those in your tank, continue this process longer and add the corals to your tank once the values are equal.  This process is known as drip acclimation.

Another important aspect of introducing corals to a new tank is to ensure they are free of parasites or other

hitchhikers.  To do this, add a coral dip to the container you have put the corals in and let it sit for ten to fifteen minutes.  Then, blow them off with a turkey baster to dislodge anything that has been killed or stunned, and inspect the corals to be sure there are no pests left on them.  This is important as they could be carrying larval forms of predators or dangerous parasites that could spread to the rest of your tank’s inhabitants.

The final step to acclimating corals is to get them used to your system’s lights.  It is also important to do this slowly.  There are four ways you can do this.  If you have hanging lights, raise them and then slowly lower them back down over three to four weeks.  You can also reduce the amount of time you leave your lights on during the day.  Cut down to four hours per day then add one hour per day each week until you are back to your regular schedule, which is typically eight to nine hours.  You can also cover the top of your tank with three to four layers of window screen or shade cloth and then remove one layer every four or five days.  Finally, you can use a dimmer to lower the light strength and slowly increase it back up over three to four weeks.  If your corals start to lighten in color, slow your process as this is a sign of stress.

It is also important to handle your corals correctly while moving them into your tank.  Soft corals should only be handled by the rock it has been attached to.  Hard corals should only be handled by their exoskeleton bases.  Small polyp stony, or sps, corals should be handled by the base where they have been cut or by the rock if they have been attached to one.

How to Acclimate Saltwater Fish

several fish in shipping bags floating in at-home tank

Acclimating Fish

When acclimating fish, you should float them in their shipping bag in your tank for fifteen minutes.  Then, use the drip acclimation process described above.  It is best to keep a towel over the container to calm the fish and prevent them from jumping out.  As with corals, it is important to ensure that the water in the container equals the same gravity, temperature, and pH as the tank before moving the animal in while acclimating saltwater fish.

Lighting is also an aspect of fish acclimation.  They do not require nearly as slow an acclimation as corals, though.  When you first put a new fish in your tank, turn your tank lighting off for four hours.  It is also a good idea to dim the lights in the room your tank is in if possible or close blinds if the room is very sunny.  Being exposed to bright light suddenly while moving can be stressful to the fish.




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Kurtz, Jeff. (2013, July 8). Acclimating saltwater fish in 10 easy steps. Saltwater Smarts. Accessed June 4, 2015 from

Thein, Than. (2013, August 28). Acclimating corals in 4 easy steps. Saltwater Smarts. Accessed June 3, 2015 from