LED lights are great, they really are the best lights we have ever had for aquariums on a variety of fronts. That said, they also pose the biggest risk and pose a particular challenge for those who have never used them before.  While manufacturers are becoming more aware of this fact, they still have yet to provide new tank owners with clear and accurate guidelines for setting up a new LED light. Light spread, spectrum, and PAR are very important to the health of your coral, all of which are controlled by your light setup. 

Not too worry! BRS has you covered with this simple step-by-step guide to setting up your new saltwater aquarium light. Most of this applies to LED lights but if you have T5s or metal halides, those instructions are far easier and we touch on that as well through the various steps. 

LED Mounts

1. Mounting

Thankfully this one is easy because most manufacturers give you a solid mounting height. This will be something like "8-12 inches from the water's surface" with the intended distance being from the surface of your water to the bottom of the light fixture. This is important because it will affect the spread of light and ensure your cover your entire tank, without losing a ton of light over the edges. If you mount it too close, the light won't spread out enough and will create hotspots. If you mount it too high, the light will spill over the edges and/or not provide the intensity you need.

Most brands will serve up mounting solutions or include the necessary hardware. You will either be mounting the light directly to the tank, or suspending it from the ceiling or light rack of some kind.  

If you are not sure about mounting height, we have a great BRStv Investigates series where Randy and the BRStv crew tested all of the most popular lights, finding the most ideal mounting height. Just visit our BRS Learning Center, hit the search bar with the name of your particular LED light, you should find the video within the top results.

AB+ Spectrum

2. Spectrum

This is probably the hardest part when it comes to LEDs, and it's going to vary based on what kind of lights you have. We broke it down to make things easy.

Metal halide and T5 Fluorescent Bulbs

The bulbs control the spectrum, so just purchase bulbs made for reef and saltwater aquariums. The product descriptions do a pretty good job describing the appearance of the bulbs. If you are using T5s, we generally recommend staying within a brand name and not mixing different brand bulbs unless you are confident in your selection. You can reference the manufacturer directly for recommended combos or check out this BRStv Investigates where Randy tests an ATI Sunpower T5 fixture with ATI brand T5 lamps.   

Tuning LED Spectrum

Depending on the particular type of LED you have, will sort of dictate which route is best for you since each light is going to have different levels of control.  Starting with the most basic to the most advanced, these options will cover 99.9% of LED lights for saltwater aquariums. 

Adjust Blue & Whites Only: This applies to basic LEDs with only two channels of control. Turn the blue channel up to 100% and then slide the white channel up only to the point at which you like the appearance.

Factory Presets: If your fixture provides factory presets, use them. Choose the tank type that most closely resembles your goals. This will usually be optimized for either SPS, LPS, or Soft Corals. You won't have to make any color adjustments, they will be preset for you. 

No Factory Recommendations: This is the most difficult situation but you have some options. If your fixture does not provide any factory recommendations or presets, most certainly don't just wing it. Messing with the spectrum controls without doing the necessary research will almost always results in an insufficient light spectrum. 

  • Copy someone with the same LED light, over a successful tank, that has the same tank goals or coral types as you plan to keep.
  • Copy AB+ Spectrum: This is pretty simple, just turn up all the blue, purple, and UV channels to 100%. Slide the red, green, and white channels to 24%.

Download: EcoTech Marine Coral Labs - PAR and Spectrum Study

Matt testing PAR

3. Adjust PAR

PAR is controlled by the output intensity. You will want to use a PAR meter to test the levels in your tank and adjust the light accordingly. We have some great content about PAR meters, the video below is the most applicable resource for first-time light testers.

Watch Video: How to use a PAR Meter the RIGHT way! This is your 5-Minute Guide to PAR Meters

If you have a friend or mentor with a PAR meter, that will be a great resource. Some local fish stores offer them for rent. We also offer both NEW and OPEN BOX PAR Meters on our website which can be a bit pricey but certainly worth it in the long run. There is a generous return policy on PAR meters with a small restocking fee, which essentially allows you to purchase it and then return it (even if you used it). Not quite a true rental program but, a similar result.

The idea is to hit the target PAR range throughout as much of your tank as possible. 

  • SPS Corals: 200 - 300 PAR
  • LPS and Soft Corals: 50 - 150 PAR

Since you probably turned the light up to its maximum intensity in the previous step while tuning the spectrum, you simply need to maintain those ratios should you need to hit lower PAR inside the tank. For example: If you started with the blue channel at 100% and the white channel at 50%, you would maintain that ratio by turning the blue channel to 50%, and the white channel to 25% to achieve half the initial output or 50% reduction in PAR.

In the case where your LED has multiple color channels, screenshot the initial settings then calculate the necessary reduction for each channel incrementally. Moving in blocks of 10% reduction for each channel makes the math easy, just requires quite a few PAR measurements until you hit the desired range.


4. Set Photoperiod

Most corals live near the equator which means they get roughly 12 hours of daylight and 12 hours of nighttime each and every day. Your goal is to mimic this total photoperiod but remember, the sun rises and falls, which creates a sort of arching effect where the light intensity slowly rises and falls through that 12-hour period.

When using LED lights that allow for ramping and saved time schedules, we slowly ramp up the lights to maximum intensity, then slowly ramp them down to 0% intensity by the end of the 12 hour period.  This will result in maximum intensity for only about 4 - 6 hours each day with a total photoperiod (time lights are ON) of about 12 hours.

When using a simple timer, as you would need for Metal Halides or T5 lights, turn on the lights for no more than 8 hours per day at full intensity.

If using a hybrid of some kind, you can create a ramping effect by simply staggering the ON/OFF times of your supplements and main LEDs. Just turn on the supplements 1-2 hours before and after your main LEDs are operating to create that sunrise/sunset effect. 

5. Leave It Alone

Once you set everything, leave it alone and don't tinker with it.  Making changes stresses out the corals and tinkering with it is perhaps the worst thing you can do. If you followed these steps, you can be confident your lighting is optimized and does not need changing in any way.