Acclimating coral to you reef tank the right way is extremely important. The stress that coral is subjected to during shipping can cause quite a bit of shock. Corals evolved to be mostly (or completely) sedentary by nature. From the moment a coral attaches to a rock or substrate, being moved about in rapid succession is the last thing on its mind.
The extremely stable environment of coral reefs adds to the ease by which they can be stressed. Frequent shifts in water parameters, temperature, lighting, and other conditions that come with shipping from the distributor, to the retailer, to your reef tank at home all take a toll on the coral – even in the best of conditions.
Knowing how to acclimate corals is an essential skill for any reef keeper looking to minimize coral stress and help their new corals regain vitality as quickly as possible!
Temperature Coral Acclimation
When bringing a new coral home, the first step to acclimating it is to bring the temperature of the bag up to match your reef tank.
A short car ride home may only cause the temperature to drop a few degrees, but each shift in parameters has a cumulative effect on potential stress. That’s why the time-honored technique of floating the bag in your aquarium to allow it to slowly warm up to ambient temperature is always recommended.
Water Chemistry Coral Acclimation
Once the floating bag has warmed up, which takes 10 to 15 minutes, you’ll then want to acclimate your new corals to the conditions of your main display tank.
There will undoubtedly be minute differences in specific gravity (salinity), mineral levels, elemental concentrations, and levels of ammonia and other pollutants that the coral will need time to adjust to.
The best way to do this is to move your warmed corals into a small container where they can then be introduced to a steady stream of water from your reef tank. Some aquarists prefer to add small amounts of aquarium water to the tank steadily using a measuring cup while others will set up a drip acclimation system, releasing a slow but steady stream of water into the container.
It doesn’t really matter which technique you use; what matters is that you’re consistent in adding slow but constant amounts of water from your display tank over an extended period.
The drip acclimation method is my favorite since the stream of incoming aquarium water is constant. Just be certain to set a timer for yourself to check on the setup every 15 minutes or so. This way, you won’t be distracted and forget to check on your corals, which can result in overflow or cold water.
How much time you give for your corals to acclimate depends on both the species in question as well as the differences in water parameters. 30 to 40 minutes is an industry standard for the vast majority of corals and other marine life. For more sensitive animals you may want to up that to 2 hours or more.
Dipping Corals for Pest Control
Preparing a coral dip is the next step in acclimation. Corals can carry a wide range of parasites and hitchhikers, some of which are visible and many of which aren’t.
Organisms like Acropora-eating flatworms, Bristle Worms, Gorilla Crabs, Bryopsis Algae, and Hydroids can all be hidden within and around your new coral. Dipping allows you to kill these creatures before they find their way into your display tank, where it’s much, much harder to get a handle on them.
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A coral dip can be prepared using the acclimation bucket or container, plus two extra containers to rinse your corals before moving them to the main tank. We need to be extra careful when rinsing because the chemical agents are fatal to hitchhikers and parasites, but also not especially good for your corals either if exposed to them for too long.
To dip your corals, simply add enough of the dip solution to the acclimation chamber, following the dosing instructions on the label.
Coral dips often have a thick, oily texture, so it’s better to swirl it about, allowing it to fully dissolve into the aquarium water, rather than clump and not reach proper concentrations.
Coral dips typically recommend anywhere between 10 to 20 minutes of soaking time, so set a timer if you need to step away. I recommend staying and watching because you’ll likely see parasites begin to flail and fall off, trying to escape the chemicals in the dip.
A turkey baster or pipette should be kept on hand to gently blow water across the coral during this process. You can then detach worms, crustaceans, and other animals as they loosen their grip and try to flee. If you don’t work to detach any hitchhikers you see, it’s possible they may survive the rinsing stage and make it into your tank.
Once you’ve fully dipped your corals, you can then rinse them in your dual stage containers. Two stages ensures that you rinses as much of the dip off as possible since the chemicals can be stressful for invertebrates such as Ornamental Shrimp and Feather Duster Worms.
Light Conditions for Acclimating Corals
If your corals have been shipped in the dark for an extended period, it’s a good idea to dim or turn off the display tank lights for the day once you’ve added your new specimens. This further reduces stress by giving them a chance to adjust not only to water parameters but lighting conditions as well.
The coral may need to increase or decrease their pigmentation, photosynthetic production, or even their place in the tank if they are a mobile species (Ricordea Mushrooms come to mind). This process can take a few days. If you can, reduce the lighting over an extended period if you know they were kept in dimmer or dark conditions for a long time. Immediate overexposure to strong lighting can lead to burns and further stress a coral so take things slowly.
Since you’ll likely be buying quite a few corals in your career as a reef aquarist, you’ll eventually become an expert in coral acclimation! There are a few more steps involved than when acclimating a fish or crustacean, but using these steps helps you avoid reef parasites like red bugs, flatworms, as well as maximizes your coral’s chances of survival during this particularly stressful situation for them!
All this aside, if you have a particular retailer or distributor that you regularly buy corals from, you may opt to skip some steps if you’re aware of the conditions your new coral is coming from.
If you know that your retailer of choice dips every incoming coral and has salinity and other parameters that match yours then you might be able to get away with simply temperature acclimating and lowering the lighting for an incoming coral.
Otherwise, it’s always a good idea to use each of the above steps to be 100% safe!