Can LED Work better than MHL ?

[Harlequinmania]

"We know MHL works, but LED can work better"

In celebration of Coral Magazine's upcoming issue focused on LED lighting, I wanted to take this opportunity to share a write up about LED lighting by Shawn Wilson (Mr. Wilson on Reefcentral and Canreef) and his company, Reef and Rainforest Design. As many of you probably know from his 300+ page thread on Reefcentral, Shawn is installing a 1350 gallon reef aquarium for the system's owner, Peter with a money-is-no-object approach.

Both are committed to providing and implementing best-practice information for the benefit of hobbyists everywhere. Here's what Shawn has to say about the processes behind the decision to use LED lights in this awesome system!

"The idea of using LEDs in the first place was something we did with great caution. I have been in the Marine hobby since 1979, with some experience in freshwater before that, so I have watched the evolution from 20w incandescent > fluorescent > mercury vapour > metal halide > compact fluorescent etc. The two new players have been plasma which we tried and passed on, and LED. We tried four different forms of LED and only one appealed to us.

We were not having any temperature problems, running consistently at 80˚F even in the middle of a heat wave. We do not use the chiller and plan on removing it some time soon. The electrical cost is always a factor, but in our case the quality of light for the corals and overall aesthetics was the main concern. The cost of lighting Peters tank with MHL was $6,000.00 and consumed 3200 watts, but we could have doubled up the fixtures if we had the room. The operating cost of lighting the tank with LED is half, but the capital cost is about $20,000.00.

To compare apples to apples, that would be $12,000.00 capital cost for MHL vs. $20,000.00 for an $8,000.00 difference. The operating cost of MHL (if we doubled up) would be $280/mo. vs. $131/mo. for LED. If we were just relying on energy savings to pay for the fixtures, it would take 4.5 years, but we are also saving in bulb replacement. The annual cost of replacing all the bulbs would be $2,900.00 ($242/mo.).

The pay off for just the bulb savings alone would take 2.75 years, so energy savings is not the main cost initiative for LED. If you combine the two ($391 savings per month), the LED upgrade is paid off in 20 months. You could also make an argument about the limited life span of MHL capacitors and lamp holders.

At no point in time was cost a major concern here. Peter is not foolish with his money, and there are a few tear stains on his check book to back that up. His concern is for the best possible reef display, even if that means tearing up what we have and starting from scratch. When I came on the scene, Peter had already purchased $14,000.00 worth of 150 watt HCI MHL fixtures.

We weren't going to change anything just for the sake of doing it, so we tested them out before making any decisions. They did score high on the quantum meter but the beam was so focused it rendered them useless for our application. The light was also very white. I'm not a fan of eerie blue tanks, but this was really white and we were getting more hair algae as a result.

If you look way back in the thread you will see some silly pictures of the many fixtures (8) that we tried over the tank (400w mogul, 250w HQI, 150w HCI, 290w plasma and several LEDs). We settled on a nice MHL unit from Aqua-Medic when we were not completely sold on LED. The wide nature of our reef formation led us to explore alternative ways of lighting the outer margins of the reef. At the time, Chingchai had just added some LED strips to punch up the colour so we decided to try some of the 120w LED fixtures we had in the Mars coral system.

We flanked the 6' MHL fixtures on both sides (front & back) and we were very happy with the results immediately. The first thing we noticed was the fish colour was much more vibrant. The high CRI also gave the corals a more natural look and the blue moon light was absolutely stunning. The ATI actinic T5 we had been using was a joke in comparison.

The 48 watts of blue LED completely eclipsed the 160 watts of T5 over the same 6' length. Peter fell in love with night viewing, and I'm not sure if Peter's wife Judy is happy with him staying up late with his new hobby!

Within 2-3 weeks we started to see some colours in SPS that were lacking before. These were corals that had been in the tank for a few months and I had thought that was their full potential. We put 16 of Orphek's PR-156 fixtures up around the tank's outer margins and pointed them in a few degrees to side light fish and corals and minimize algae on the viewing panels. We were happy with the hybrid of MHL & LED but after a couple of months, we decided to experiment by taking out one 6' MHL fixture and see if colour would improve. It has been about a month and the pure Orphek LED section of the tank has the least amount of algae on the glass and the nicest coral pigmentation.

The lack of nuisance algae, energy savings and cooler operating temperature means that we can extend the photoperiod by a few hours so corals can grow more and we can enjoy the tank more. The extra blue moonlights in the middle really make it worth the switch. We have started to buy more night glow corals for their fluorescence. Like anything in the reefing hobby, it has to be in balance; we have some corals like blue zoanthids that look great during the day, but become invisible at night, and conversely some yellow polyped acros that look dull during the day and explode at night.

We are planning on replacing the other two MHL fixtures soon with additional Orphek fixtures. We are just waiting on some new dimmable drivers from the manufacturer. Unfortunately, the space above the tank is very limited so multichip pendent LEDs like Orphek's DIF series are not an option. I prefer the idea of a multichip and believe that is the direction the hobby is going in.

They don't create weird blue & yellow shadows the way some LED fixtures do, the footprint is smaller for better viewing from above, and the shimmer is more realistic. A homogenous all-in-one chip is the way of the future and much more efficient than a mix and match of red, green, violet, blue and white chips scattered randomly over a pegboard.

Here is the criteria we looked at when evaluating LED lighting technology along with some general tips...

1) Make sure the light does not cast weird blue and yellow shadows under rocks and corals.

2) Look for a calming shimmer rather than the rapid flicker that is generated by some LEDs.

3) The light has to look natural, as if it was sunlight, not artificial, cold & clinical like some LEDs and T5.

4) Some emitters have a narrow spectrum and coral pigmentation is lacking in blue, purple and red, but green is vivid. Do a search and find other hobbyists who are using the light and see what their coral colour is like.

<br style="padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">5) The CRI (colour rendering index) has to be high so fish and corals look natural and the sand is white, not blue.

6) Take a look at the spectrograph and see if it shows a lot of green & yellow light which is of little use to coral. This wavelength is put there so we recognize it as "bright" light for home and office applications. The green/yellow peak encourages nuisance algae and browns out corals with too much zooxanthellae. This peak lowers the PUR value.

7) The pegboard design creates hot spots and deficiencies with one green here and one red there (Lightbright) configurations. An all-in-one chip is homogenous and much more efficient.

8) Some manufacturers use tight 40˚ optics to fool quantum & LUX meters then use wider 70˚ optics on the outside to make it look like coverage is better (at the cost of intensity).

9) Some lights have a high percentage (often > 50/50) of blue LEDs which also give false high PAR readings.

10) Try to find a fixture that gives you the aesthetic you want for a reasonable price. Some feature heavy models are priced beyond reach and offer features that you may never utilize.

11) As with MHL, find a high kelvin white chip mixed with some blue and perhaps violet emitters for extra punch. A 7,000k LED is no better than using a 7,000k MHL bulb.

12) Pick a manufacturer who is developing new products and moving the technology forward, not just rebranding generic fixtures with standard industry components.

13) Take a look at who is using the product. Are they seasoned reefers with a lot at risk, or are they newbies who are trying products without doing thorough research and experimentation.

<br style="padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">14) Review the pictures on the manufacturer's website. Often they are the owners tank and the coral colour is still weak.

15) Pick an adaptable technology where you can upgrade drivers and emitters, as the technology continues to grow, such as multichip LED.

We know MHL works, but LED can work better."

Thanks very much to Mr. Shawn Wilson for this work of art and for pushing the boundaries of the hobby and sharing his findings with us all in great detail.

** Article extracted from coral magazines