In my experience, corals need to be acclimated, just as fish or inverts would need to be when adding them to your aquarium.The below process is what I would typically follow when acclimating corals to my tank.Although I do not quarantine my corals, I will give them a preventative treatment dip to rid them of potential hitch hikers.I also carefully inspect any coral before purchasing it when I buy it from a store or even from another hobbyist.If I do notice hitch hikers on the coral, or the tank the coral doesn’t look healthy to me, I will not buy the coral.This is also the reason why I do not like to buy corals on-line as I want to personally inspect the coral before I decide to buy it. If you do choose to quarantine your corals, I would suggest to use the below process to acclimate the coral to your quarantine tank repeating the same process when you move the coral to your display tank.

Step 1 – Float the bag

I will keep the bag I got the coral in closed and let it float in tank water for about 30 to 45 minutes allowing the temp of the water in the bag to become the same as the tank water.If I am floating the bag in the tank, I will lower the lighting level to about 10% of normal.Most of the time I will float the bag in the sump were the lighting level will be very low just so I do not have to change the lighting in my tank more than what I have to

Step 2 – Remove the coral and water

Once I am confident the temp of the water in the bag matches the tank water, I will remove the coral and the tank/bag water from the store and place them both in a separate container.  I have a few different sized containers that I use to accommodate different sizes of corals and different amounts of water.

Step 3 – Acclimate the coral to your water parameters

Now that I have the coral in a different container with the tank water from the store, I will start adding tank water to this container.  I will typically add about ½ cup of water about every five minutes or so.  Once the container has become full, I will remove and discard about half the water from the container so I can continue adding water from my tank to this container.  I will repeat this about three times or until I am comfortable that I have replaced all of the water from the store with water from my tank

Step – 4 Observation

While I am adding water from my tank to the container with the new coral in it, I will be carefully watching the coral for any hitchhikers.

Step -5 Treatment dip

I will always give the corals a preventative treatment with a coral dip before placing them in my display tank.The below is the coral dip that I like to use. Just make sure that whatever coral treatment dip you choose that you careful follow the instructions on the bottle.If I noticed any hitch-hikers while acclimating the coral to the tank water, I will ensure they are removed / killed off by the coral treatment dip.If I see any harmful SPS crabs, I will get a pair of tweezers and manually remove them as these crabs are very hardy and some of them can survive the coral treatment dip.

I can not stress the importance of using a coral treatment dip enough.  I once skipped this step and introduced flat worms into my tank.  It took me a very very long time and a lot of effort to get the flat worms under control.I will never make that mistake again.So far, I have been very successful keeping hitch hikers out of my tank by using a coral dip.

Step 6 – Add the coral to the tank

Once I am confident the treatment has removed any potential hitch hikers, I will lower the lighting level in the tank to about 1/3 of normal (if not already lowered). Next I will remove the coral from the current container and place it in a second container of water that I just removed from my display tank.The reason for this is to remove any trace amounts of the coral treatment before placing the coral in my tank.I will gently swish it around a little in this second container before removing the coral by hand and placing it in my display tank.All corals will initially be placed on the bottom of my tank

Step 7 – Acclimate the coral to my tank lighting

Now that the new coral is in the tank at a lower lighting level, I will leave the lighting at this current level for a few hours.I will slowly increase the lighting level back to its normal level over the next 2 or 3 hours.Before switching to LEDs, I would place 4 or 5 layers plain of white paper on top of the tank lids to block out some of the light and slowly remove one layer at a time allowing more and more light to get to the tank.
The next day, once the tank lights are on at their normal setting, I will place the coral in its intended spot.If the coral is a sensitive or high light demanding coral requiring it to be placed higher in the tank (closer to the lights), I will take a few days to move it up to its intended spot, placing it a little higher on the rocks until it has reached its intended spot.

NOTE: I will never add any of the water that I used to acclimate a coral back into my tank.Once I am done acclimating the coral, I will top up my tank with some freshly made salt water to replace what I had removed during the acclimation process. I will always discard all water used to acclimate a coral.