Appropriate acclimation is essential to the survival of any new coral entering your system, this is due to the fact the coral will have experienced a significant amount of stress during transit.
I recommend that you follow the below procedure immediately once your coral has been received.
Step 1 - Switch off your tank lights
For the last 18 hours, your new coral has been in complete darkness and will need to adjust to the bright lights above your tank. For this reason, turning them off is a good idea as it completely eliminates a potential source of stress. One of the most common ways to kill a new coral is exposing it to too much light too quickly, therefore, I feel this is one of the most important steps.
Step 2 - Place the coral and all the transport water into a larger container
Corals are shipping in small plastic containers or bags, by placing them into a larger container which still allows them to be submerged in the original water, you are allowing yourself additional room for the next step.
Step 3 - Added aquarium water to the new coral
Over the next 30 minutes, slowly add water from your aquarium to the new container. Corals are don't handle rapid changes to certain parameters and this process makes that change far more gentle. Please be mindful though that during this state the temperature of the acclimation water can drop slightly and needs to be taken into consideration. For this reason, I don't advise that this process takes longer than 30 minutes.
Step 4 - Dip your corals
Although many of you will ignore this step, this is vitally important for the long term success of your reef tank. All my corals are dipped, using Coral RX prior to entering my system and I also have 7 wrasses as part of my pest death squad.
Despite this, it virtually impossible to guarantee that all threats are eliminated, therefore I strongly advise you dip them prior to them going into your tank.
Step 5 - Place the coral in your tank
After completing all the above steps, it now time to place the coral in your tank.
It will still need a few days to adjust to your lighting, therefore I suggest somewhere low down or half shaded is a good place to start. After it's been in your tank for a couple of weeks, it's then time to decide where you want to place it long term.