Calling All DIY LED Experts...Need Help w/ Non-Standard LED Build

Hey gang long post I'm afraid, but if you know a thing or two about LED's and have a few minutes I could use some help.

Currently all of our holding and prop tanks are lit by T5's...soon it's going to be time to think about replacing bulbs again. I'm thinking I should look at investing this money in LED's instead. My dilemma is because of how our tanks are set up there are no "ready made fixtures" that would work well...they would be overkill in too many ways...so I'm looking to DIY something custom...but even then all the various DIY builds I've looked at are for more "standard" tanks. Our tanks are setup in long shallow raceways so the "general rules" I see for optics and number/placement of LED's just don't apply very well.

So here's what we are working with. The majority of the raceway's are 12 feet long and about 32" wide and are comprised of 8 tanks in 2 rows. Here is a photo so to better illustrate the setup.



As you can see above the original lighting setup was a row of T5 2 bulb fixtures over each row of tanks. This proved to be WAY too much light for the systems that house LPS and softies...each LPS/softy raceway is now lit by a single row of T5 fixtures down the middle of the two rows of tanks and they have been raised up higher to allow more light "spread" to either side. Because the tanks are shallow this actually provides not only enough light to maintain the corals, but pieces that are cut and propagated actually show good growth. Bear in mind this is for LPS and soft coral at this point. The SPS/clam/nem systems are configured a bit differently and I'll deal with those later.

So on to my LED "needs". I'm thinking I would like to build "fixtures" from aluminum channel that are the full 12 feet long. I think it makes sense to space the LED's so they are "clustered" over each individual tank (no need to light the spaces in-between". Each tank is 32"x14"...now here is the real catch, and where I'm having trouble...the tanks are very shallow...once you take into consideration most corals are placed on elevated eggcrate there is only 4"-7" inches of water from the surface to the eggcrate...and even less to the top of the coral. Does anyone want to give me an "educated guess" on what number/spacing/optics would work for this? I don't want to "overkill" this. The goal is to be able to maintain/grow the coral just as well as we do currently with the minimum number of LED's and offer a good energy savings as well. I already run energy efficient pumps etc., so this is one of the few areas I can potentially cut back energy usage. Right now each raceway uses 6x54W T5's...so I'm currently consuming 324W per 8 tanks in a 12 foot raceway. If I modify most of what I see in various LED builds I end up using almost that much power, so I'm thinking I can get away with less LED's that my original plans. I'm really having trouble getting my head around this and I don't have enough extra cash to experiment a lot...I really need to have a fairly solid plan in place before I start.

If you've made it this far, thanks for reading. Any help/suggestions are appreciated.

 

Well unfortunately i have 0 experience in DIY LEDs but i know some.. I think a dimmable driver would be your best bet Rapid LED has all you need, get in contact with them for your best results, i hear they know their stuff... if you want run optics on only the blue-er led and have the white with none, this way it wont be as "direct" for your coral.?? I like the idea with the aluminum channel and having them clustered over the tank.

Good Luck!

 

Thanks for the response...I'll try to catch the guys at Rapid after the holiday.



Here is a very quick/crude diagram of how things are setup currently, maybe that will help people to visualize what I'm working with better.

The black area is the complete raceway and measures 144" x 32"

The blue are the individual tanks which measure 32" x 14" each.

The red are the current 2x54W T5 fixtures that run down the middle of the raceway.





Maybe I'm wrong, but I didn't think LED's would able to cover the same area if I was to run them down the middle in the same fashion as the T5's. I was thinking I would need to run a separate LED "fixture" over each row of 4 tanks to get good even coverage. I also figured I could "cluster" the LED's over each tank so I'm not wasting LED's over the areas that are between tanks. Based on the fact that 2x54w T5's over each tank was too much light and bleaching corals, I don't want to end up with too many LED's and repeat a costly miscalculation. For the time being I'm just trying to get my head around these systems for LPS and softies...the SPS/nem/clam systems are setup differently so I'll deal with them later. I just concerned that I may end up with too much light given my past experience and the extremely shallow tanks. Using the "standard" one LED every 3" or one LED for every 10"-15" square inches just seems to give me a lot of LED's and more power consumption that what I currently have in T5's...and that just doesn't seem right. On the other hand I don't want to skimp and end up with too little light either, UGH!

 

Generally, LEDs will be in increments of 12 if your using typical CREEs, with meanwell drivers. If you spaced them a bit, 12 may almost cover the tank, minimally though, for what your describing. You're probably better off going with more and dimming them for two reason. One, you have more control and 2, LEDs, loose intensity slowly over time. So, just because you have enough now, doesn't mean you will in a year or two. I think 18 per tank would work if spaced quite a bit ( two tanks would have to share a driver for 6). The problem with LEDs, is even without optics the PAR drop off is substantial. There is a huge hotspot. To avoid a really big hotspot, you need to space them. You should get the most even illumination If you space them, at the points where the PAR has dropped off 50%. Does that make sense? This should also be the most efficient configuration for your setup, as your not wasting any excess PAR in the hotspot and therefore don't need t make up for it on the edges by running more juice. Also, even though you don't need punching power, you may need optics if they are hung higher. Without optics, you'll end up leaking most of the light, over the sides, if you go more than 12" or so, up.

Remember from high school trig, the the total coverage of a lens is TAN(lens angle / 2) * height * distance. However, with LEDs, this is the total coverage, but the PAR within this coverage can drop off substantially from the center to the edges.


18 is a guess though, personally, I'd get 24 leds and 2 drivers and play around a bit. build a fixture, at the height and spacing you want. If it's high, try with maybe 80deg optics and with out. Maybe tape off some LEDs with black electrical tape or use the plug and play LEDs or something, until you get similar PAR to the T-5s, at maybe 75% power. This way you have a little more than you need, but are okay if you ever need a bit more or when you start to loose intensity. In the meantime, you can dim them. And of course, if this works for you, send me some corals for my consulting fee ;D

 

Hmm, that is a bit of a unique situation.

As Matt has said (just above me), you'll really want to space them out over each tank.

I'd use no optics at all, since your tanks are so shallow. I think even 80deg would give you spotlighting and super intense hot-spots.

18 per tank would absolutely be enough, but with no optics, even spacing, and such shallow tanks, 12 might well be enough. I'd just be concerned about sufficient and/or even spread if I only used 12 per tank however.

 

With the ammount of leds you'll be using I don't think I'd use the meanwell as you would end up with so many of them. I would check out the Thomas research drivers from Nanotuners.

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