Finding the right height to mount your reef tank lighting, specifically LED lights, can be confusing because the advice is often conflicting. The reason this gets a bit tricky is because every tank is different in size, shape, depth, what is in it, the lights themselves and how they are used. All of this will have an impact on finding the right mounting height for your LEDs.


Orphek Atlantik LED over a reef tank


When it comes to mounting height, there is simply no one right answer.


Thankfully, with the human eye and a bit of intuition from the facts we share with you today, you can find a near perfect mounting height for your individual tank and lighting solution quite easily.


Kessil A360w LEDs over a reef tank


Intensity vs. distribution

Mounting height does have an impact on PAR but the controllable nature of LEDs give you the power to adjust intensity to match your desired PAR value.


Mounting height is more about spread and even distribution of light as opposed to PAR intensity.


The higher you mount the LED lights, the better the spread and quality of light. As you move LED lights away from your tanks surface, hot spots will be reduced, the spread of light will become wider, shadows will become less drastic and spectrums will blend better.


Example of light spill from an LED light fixture


The inverse of that is the higher you go, the more light spill you get into the room. As the light spread becomes wider and wider, at some point the light starts to spill over the edges of your tank which is less than ideal considering the aesthetics and the idea of wasting precious light.


To find the perfect balance for your tank and light, start with the manufacturer recommendation for spread then adjust to accommodate your tank size and priority.


Adjusting Kessil A360X LED mounting height


Priority #1 - Lighting your tank for efficiency

The first priority is lighting the tank in the most efficient or economic manner. Meaning purchase the fewest number of lights and consume the least amount of energy during operation while still providing sufficient coverage.


The goal in this case is to get as much of the light into the tank and as little into the room as possible. So that just means raising the light until you start to get light spill and go no further.


This approach may not result in perfect distribution or blending but that may not be required for your tank. A typical mixed reef containing soft corals, LPS and a few logically placed SPS is simply not as reliant on an evenly distributed blanket of light compared to a SPS dominant tank.


Mixed reef aquarium lit with LED light


Priority #2 - Lighting your tank for maximum spectral qualities

The second priority accommodates those SPS tanks and focuses lighting the tank in a way that maximizes the spectral qualities of blending, distribution and shadow reduction with cost and number of fixtures being secondary.


In this case, raise the lights until there is considerable or obnoxious amounts of light spill into the room because the light will blend and become more evenly distributed the further away you go. This will be a much higher mounting height than the priority #1 in most all cases.


Randy measuring mounting height on WWC 500 gallon SPS display tank


For example, World Wide Corals hangs LEDs anywhere from 16 to 24 inches from the water’s surface over their displays. This is done with light distribution, even intensity, reduction of hot spots and spectrum blending in mind, not maximum efficiency or lowest initial cost.


EcoTech Marine Radion XR15s mounted over BRS lobby tank


One caveat to this is that the nature of LEDs output allows you to use multiple, lower wattage fixtures and mount them closer. This will achieve similar intensity, distributing and spectrum like what you would get using a single high-wattage fixture mounted further up.


Lighting rack with x4 Aqua Illumination PRIME LED lights


Learn more

We did a BRStv Investigates with Aqua Illumination Prime LEDs that compared the PAR distribution between a single and multiple rows of lights to identify the best configuration for optimizing lighting conditions for SPS. We gathered some valuable data during this test which was an integral part of our journey to understanding how to best light a reef aquarium.


WWC 300 gallon mixed reef display


Another excellent lighting video is Episode #11- Reef Tank Lighting Made Simple in our video collaboration with World Wide Corals. Combining the experience of World Wide Corals with the knowledge and methodical approach of BRS, we created what we feel is one of the most comprehensive lighting videos to date. Regardless of your experience level or chosen lighting system, we are confident you will walk away with some beneficial information that can be applied to your tank.