Why Is My Acropora Coral Peeling ?

It has happened to almost every reef keeper.  You wake up one morning and take a look at your tank and notice that one or more of your prized acropora corals is peeling.  Since acros are sensitive corals there are many reasons why this could be happening, but a few quick questions and tests should be able to help narrow down the cause.

How Widespread Is the Peeling?

Is the peeling only affecting one colony or the whole tank?  Is the peeling happening fast or slowly?  The answers to these questions can help determine whether it is an issue with a single coral or a larger tank issue.  If the peeling is confined to a single coral, then causes to be considered are lighting, flow and pests.  Any recent changes to the lighting schedule, flow rate or even the rockwork could be negatively impacting the peeling coral.  Issues with flow usually cause slow peeling, whereas too much light can cause extensive damage quite quickly.  If there have been no changes in flow or lighting, then the damaged coral should be checked for pests and removed from the tank and dipped if necessary.  Dipping can help to save the undamaged parts of the coral as well as prevent pests from spreading.  However, if the peeling is more widespread then it is time to look at water parameters.

Check the Water

Since acropora are sensitive corals, they require stable water parameters and are especially susceptible to fluctuations in PH and Alkalinity.  If the tank is equipped with a Neptune or similar monitoring system then the PH and Alkalinity level history can be checked for any dramatic swings.  PH levels tend to fluctuate more at night, which is often the reason why peeling is first noticed in the morning.  On tanks without monitoring systems, the PH and Alkalinity levels can be checked through manual testing.  It may also be worth considering increasing the frequency and size of water changes.

Can Peeling Corals Be Saved?

Generally speaking, the parts of a coral that have peeled will not recover and are considered dead.  However, it is possible to save the colony by cutting off the damaged portions.  However, it is important to address the underlying cause to prevent the damage from continuing.

What Else Can Be Done?

Fragbox offers ICP water testing that can help identify water chemistry issues that are not apparent on home tests.  It may also be worth checking the sump or rear chamber for damaged equipment that may be rusting or leaching chemicals.  The use of household air fresheners or sprays near open top aquariums has also been rumoured to negatively impact corals.  While the reefing hobby comes with inevitable ups and downs, being able to identify the source of problems is a major step in addressing them and hopefully avoiding them in the first place.