How to Properly Acclimate Your Corals to LED Lighting

One issue reef hobbyists may encounter when using new LED lights is corals bleaching or quickly losing their brilliant colors. This is often due to stress caused by not allowing the corals to get properly acclimated to the new lighting intensity and color spectrum. When a coral bleaches, it is not dead, but it is under extreme stress and can die quickly.


Coral bleaching occurs when coral polyps become “stressed” and expel their symbiotic zooxanthellae (which is what gives them color). This often leads to a lighter colored or completely white appearance – hence the term “bleaching.” In nature, bleaching can be caused by a number of factors, including:

  • Increased (mostly due to global warming) or reduced water temperatures
  • Increased solar brightness (PAR and ultraviolet light)
  • Changes in water chemistry or salinity
  • Bacterial infections
  • Sedimentation, silt and runoff
  • Oxybenzene and other sunscreen ingredients that are non-biodegradable and can wash off of skin
  • Herbicides


In reef aquariums, these same factors can also cause coral bleaching, especially an increase in light intensity. Switching from fluorescent lights to LED lights can often cause a dramatic increase in PAR or a change in color spectrum, so it’s very important to slowly acclimate your corals to new lights.

We’ve put together some simple tips on how to acclimate your aquarium and corals to LED lights. It doesn’t matter if you are going from fluorescent lights to LEDs or just upgrading to a new LED light; slow acclimation is HIGHLY recommended for any changes in lighting.

Here are a few simple tips to slowly acclimate your aquarium to new LED lighting.

1) Raise your light fixture. This method is best used if your using a hanging kit or mounting arms like our Adjustable Tank Mount Brackets. Increase the mounting height and slowly raise your light fixture over the course of 1-2 weeks.

2) Reduce your photoperiod. Most hobbyists run their aquarium lights a total of 10-12 hours per day, including a 1-hour sunrise/sunset. You’re safe to still run your sunrise/sunset lighting for the same time, but you should consider reducing the amount of time that your daylight spectrum runs. Reduce the time period down to 7-8 hours per day instead of 10 hours. Add one hour of daylight every week until you’re back to your original lighting schedule.

3) Lower your daylight light intensity. This is usually the easiest method for acclimating your aquarium and corals to their new lights. Simply lower your daylight intensity by 20-30% and gradually increase the overall daylight intensity by 10% each week until you are back to your original light levels.

No matter which method you use, always watch your corals to see how they are reacting to their new lights. If your corals begin to lose color and start turning white – slow down! Taking your time and being patient will always lead to a healthy, thriving reef aquarium and allow you to experience the full potential of your new LED lights.