PAR & Reef Tank Lighting Schedules: What's The Ideal Output Intensity For Your LED Light? - BRStv Reef FAQs

Slide and pray is becoming a tired story about reefers trying to find the right PAR values and reef tank lighting schedule. The proven results with simple plug and play T5 and metal halide lighting is a thing of the past because the high-powered LED lights of modern reefkeeping gives users complete control over intensity, photoperiod and spectrum.


Programming LED lights using sliders


In our latest Reef FAQs videos we set out to show all of you our best tips and tricks for setting LED lights for success without investing in really expensive meters or going through the pains of costly trial and error. In this episode we approach PAR or intensity as well as photoperiod to help you dial in the right amount of light for your tank.


Here’s the facts

The intensity sliders ranging from 0-100% are a popular option used by manufacturers to give users control over LED light spectrum and intensity. These slider percentages really mean nothing in terms of actual measurement of intensity/PAR or how to set your lighting schedule.


BRS160 Aquarium


The process of finding the desired PAR can be difficult because the human eye is a terrible judge of brightness and even worse yet, judging true PAR values.

In order to create the PAR values you need inside your tank, there are three options or approaches. Among these methods, some are more difficult than others and they are presented in an order from lowest chance of success to highest.


Kessil LED Light App


1. Just wing it

You can simply adjust the intensity of the lights until it looks or feels right. In this case, success is going to be based on one of three things.


1. You are a very experienced reefer and can just do this intuitively based on experience.

2. You got lucky and chose a level of output that landed within the required PAR range for your corals.

3. You chose the right tool for the job and followed instructions; a reputable LED chosen correctly based on manufacturer recommendations for tank size and mounting height.


Scenario #1and #2 are straightforward and, honestly, will give you the lowest chances of success.


Option #3 is going to be the best approach within the “guessing” realm because the best aquarium LED manufacturers are using the years of experience we now have to make more accurate recommendations.


Bleached Coral


With LED’s you are just as likely to kill a coral with too much light as not enough. It’s just true.


Some of the options that seem to be balanced better for the application are the “Medium” models.


EcoTech Marine Radion XR15

Aqua Illumination Hydra TwentySix

Kessil A360X


These fixtures come from the industries best lighting companies and are capable of supporting anything from a soft coral tank with polyps to a full blown SPS tank without easily overpowering it.


The higher powered options require a more advanced approach to get the spread and intensity right and there are significant advantages to using multiple lower wattage fixtures as opposed to one high-powered fixture over your tank, most notably the ease of setting intensity and the even distribution.




2. Ask someone

This is a giant leap forward in terms of success rates; just ask someone who is having great results. There are no shortage of successful reefers with your coral type, tank size and preferred lights on Reef2Reef, the #ASKBRSTV Facebook group or even local aquarium clubs.


If you ask for recommendations online, you can often get answers within minutes for intensity, spectrum and photoperiod. Just make sure you are impressed with their results first and mission “Program PAR” is accomplished.


Randy using a PAR meter to measure PAR inside WWC display tank


3. Measure PAR

You guessed it, the highest percentage path to success is to pick a PAR goal and measure your lights output using a PAR meter. Despite being the best way, using a PAR meter is the least common method mostly in part to the fact that PAR meters are expensive.


PAR Meter


NOTE: The PAR meter rental program mentioned in the video is no longer available. We do, however, offer an extended 60-day return policy on the Apogee MQ-510 PAR Meters that allows you to return a USED meter within 60 days of purchase for a refund minus a restocking fee. There will be a $100 restocking fee charged for all returned PAR meters in used condition. 


Based on our own experiences and the information World Wide Corals has shared with all of us, an SPS Acropora dominant tank should be getting 200 - 300 PAR throughout as much of the tank as possible.

There will be peaks and valleys directly under the light and in the corners based on the simple nature of LED light output but a PAR meter is going to help you find the sweet spot for your particular lighting choice and tank size.


PAR values in WWC display tank


A handy trick is print out a photo of your tank, then record the measured PAR numbers in various spots throughout the tank. Then adjust your light placement and intensity to find the most even coverage within the desired PAR range.


Coral placement can be something you address and experiment with after documenting the actual PAR values in various areas of your tank.


In LPS or lower light demanding tanks the target is 50-150 PAR throughout the tank and often the lower the better.

PAR is absolutely not horse power with most LPS corals and getting the PAR that low with LED’s can actually be a challenge, especially if you rely on your own eyes. Many popular LED lights need to be dialed down by 25% - 30% to land in this <150 PAR range for lower light demanding corals.


Example of LED light schedule graph



Once you get intensity right, you need to set a schedule. If you plan to push the limits and run with higher PAR values, our best advice is to limit the photoperiod to about 9 hours.


If you running on a more conservative or lower range of PAR for your corals, 12 hours is probably better. This is all about providing the nutritional requirements for the corals as well as providing restful dark time to free themselves of the toxic byproducts of photosynthesis.


WWC display tank under heavy blue lighting


Ramp Time

For ramp time, it is nearly all visual to have a classic sunrise and sunset effect. While it is true that the sun naturally rises and falls creating varying levels of light throughout the day, in the ocean corals are actually protecting themselves from the sun with slower photosynthesis through the peak hours of the day.


So feel free to ramp up and down over 15 - 30 minutes or even longer for an extended period. The idea is to run moderate PAR for 12 hour schedules or more intense PAR for 9 hour schedules with about 1.5 hours of relatively low PAR on both ends of the photoperiod.


A 12 hour schedule lets you enjoy the tank for a longer period of time. The ramp down can be an amazing time to view the tank because the corals will be open and reducing the white colored light will allow the coral fluorescence to shine through and really pop. This is also a great time to feed corals, observe fish and just sit back to enjoy the fruits of your labor.


BRS office tank using EcoTech Marine Radion XR30W


Your on the path to becoming an LED lighting expert and be sure to check out our Reef FAQs episode all about LED light spectrums to find the best possible mix of color for your tank.


Here at BRS we release videos and accompanying articles each and every week so be sure to check out the content area of our homepage regularly for the latest educational reef aquarium content from Bulk Reef Supply.

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