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Why Does My Coral Have White Tips?

by Brian Dunleavy
Why Does My Coral Have White Tips?

Are your SPS corals displaying white tips and wondering if you should be worried? White tips on corals are not always a cause for concern, as they may be natural growth tips. But, it could also be burnt tips or tissue necrosis, which in that case, you should be slightly worried about.

Corals go through a lot of stress. From transportation to your home to settling into an aquarium environment, so there is plenty of space for your SPS coral to experience different conditions. Therefore, you must introduce your SPS coral slowly to adapt to its new home and recover from traveling. 

The good news is, if your SPS coral has started turning white, do not worry as we are going to go through the reasons why it may have happened, if there is anything you can do, and what conditions will prevent corals from becoming stressed. 

Four Reasons Why Corals Get White Tips

There are four main reasons that corals may get white tips:

  1. Growth Tips
  2. Coral Bleaching
  3. Alkalinity Burn
  4. Slow Tissue Necrosis

#1: Growth Tips

White tips are not always a problem, they can simply mean your coral is growing healthily. 

White tips are commonly seen in the wild, particularly on shallow reefs with Acropora corals. As SPS corals grow, they exhibit white tips because of accelerated growth. So, as long as your coral still has healthy polyp growth around the white tips, it’s a good sign. 

So, why does this happen?

As corals grow, the calcium carbonate skeleton stretches and become exposed until zooxanthellae populate the new growth areas and undergo photosynthesis. Zooxanthellae are microscopic algae that give your coral its beautiful color. Without the zooxanthellae giving your coral its pigment, it can cause your coral to turn white. 

#2: Coral Bleaching

If the white tips start to move toward the base of your coral, you may be bleaching them. Bleaching occurs when the temperature is too high and/or the lighting is too bright. 

First, check the lighting level inside your aquarium. SPS corals grow best under medium to high lighting with a PAR level between 200 and 400, but, always check the requirements for your particular SPS coral before adjusting the lighting. 

If the lighting is too high, gradually turn down the lighting and give your coral time to color back up. 

#3: Alkalinity Burn

Alkalinity burn, commonly known as burnt tips, happens when nutrient levels inside an aquarium are too low and the alkalinity level increases exponentially, turning the tips white. 

If it is an alkalinity burn, the surrounding coral polyps will appear patchy with some tissue loss around the white tips. 

Test the alkalinity level inside your aquarium. The ideal alkalinity level for SPS corals to thrive is 8.0 dKH, yet between 7.5 and 9 dKH is also normally fine for most types of SPS corals, as long as tank stability is maintained. 

Alkalinity burn usually resolves on its own once the alkalinity level is stable again, and if you catch it early on. If your SPS coral is struggling, try fragging off the burnt white tips to prevent it from further spreading.

#4: Slow Tissue Necrosis

Slow tissue necrosis (STN) is the bane of every aquarium hobbyist. It can take anywhere from days to months to attack your SPS coral, and you must take it seriously to prevent losing your coral. 

Slow tissue necrosis is thought to be caused by a protozoan that attacks the coral’s tissues and skeleton, often causing it to turn ghostly white. 

Look closely at your coral. STN starts at the base of the coral, slowly spreading toward the tips. Very serious STN strips the coral’s polyps exposing the skeleton, and unfortunately, this is bad news. If your coral’s skeleton is exposed, it can suffer from secondary infections and excessive algae growth. But, wait, as the nightmare doesn’t end there…

STN infections are easily spread inside the aquarium water. This is why it is essential to quarantine new corals before adding them to your aquarium. This allows you to check that your coral does not have STN and other coral diseases.  

The exact reason behind STN is still not known, however, the common issues associated with STN are listed below:

  • Drastic changes in alkalinity
  • Swings in salinity and temperature water parameters
  • Low alkalinity levels
  • Bacteria 

If you are lucky, STN will stop without intervening, but most corals require a coral dip to prevent them from getting progressively worse. Some corals may be too far gone to save, and as difficult as it is, the best option with serious cases of STN is to throw your coral away to prevent other corals from getting sick. 

Water Parameters For SPS Corals

To prevent your coral from getting bad white tips, tank stability is key. You should focus on alkalinity, nitrates, phosphates, and calcium in particular. 

High phosphate levels can inhibit coral growth, mostly SPS corals that require a higher level of care. Healthy phosphate levels in a reef tank should be <0.1 ppm. 

Nitrates should be 5 to 10 ppm. 

Alkalinity as mentioned above should be between 7.5 and 9 dKH, but the ideal level is 8 dKH. 

Calcium levels for SPS corals should be kept between 380 and 430 ppm, but you should aim near the top of this range. When calcium levels drop below 380 ppm, white tips can appear. 

How Long Does It Take For Corals To Recover From White Tips?

White tips do not fix themselves overnight, and it all depends on your aquarium’s conditions. However, if you have experienced bad white tips, but have stabilized the tank parameters, you should expect the following recovery times:

  • Bleached Corals: 3 to 6 months
  • Alkalinity Burn: Weeks to months
  • STN: Days to months


If you have walked up to your display tank and noticed white tips on your coral, do not panic, as they may just be growth tips. However, if your tank conditions and parameters are not right, it could be alkalinity burn, the start of coral bleaching, or in worse cases slow tissue necrosis. 

Tank stability is key in the hobby, and this should always be your “go-to” for treatment before chemical coral dips and fragging parts off your coral. 

If you have any questions regarding which lighting will best suit your corals, or what beautiful coral frags we have to offer, do not hesitate to contact the team at Reefco Aquariums

by Brian Dunleavy