# My LED Plan



## slipperheads (Oct 17, 2007)

Scenario:

Tank Dimensions: 4' long, 18" wide, 4.5' high.

I've done quite a bit of digging for a couple of days on LED lighting. For me, I need the penetration from LEDs more than anything to get the appropriate lighting and coloring of plants. Broms need ~2500 lumens hitting them to maintain their color, as I have researched, which means I would have to start with quite of lumens from the top of a 4.5 foot tank. 

I have been looking at DIY LED articles but none that tap the extent of knowledge I'm looking for: wattage per LED, how many I need for the tank, on and on and on. Assembling the thing seems doable if I just understood what I need, but information out there makes assumptions of what the reader already knows (which is too much for me).

SO, I am looking at rigging together some LED strips on top of the tank in maybe 6 or so rows of white/ warm light (4:1 ratio). 

Above anything, I need enough light penetration into the tank. I assume 3W LEDs are appropriate for this, maybe more? 

Here, for example, is a 3.75W/LED strip for sale:
2 Pcs Cool White 15 LEDs 11 8" 0 3M 5050 LED SMD Light Lamp Strip 12V DC 3 75W | eBay

Alternatively, Kutop has their strips for sale here:

5 meters 300 LEDs flexible SMD 5050 LED light strip

It does not say the wattage per LED, but I assume since the 5 meter strip is using 72watts, 72watts/300 LEDs = ~.24W/LED ?? Is that right?

Seems like the ebay one is a good deal to me for 3.75W/LED, but again I am running it with you guys. I am interested to hear about light penetration (Wattage per LED I need for 4.5' height) and maybe some product suggestions you might have.


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## NathanB (Jan 21, 2008)

4.5 FT high? 
Those leds will not have the power to reach that far. I have them on 5g aquariums and they are not bright enough. You want to use the cree or new philips leds for something that size


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## easternversant (Sep 4, 2012)

I think you'd be much better off with a DIY option over those. You could use Cree XP-G 5w diodes and probably get really good penetration. I'm currently running mine at ~75% driver capacity (which is below LED capacity), further dimmed down to 25% brightness on a controller and it is bright. I imagine if you do a string or two of these you'll have plenty of light, though you'll want a fan eventually.

See my as of yet unfinished LED build. I got sidetracked and didn't resume it, but will!


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## slipperheads (Oct 17, 2007)

EDIT: Looks like the eBay strip LED is 3.75 for each strip, which leaves it to be ~.25W/LED, or about the same as Kutop.


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## slipperheads (Oct 17, 2007)

Easternversant, It seems we are both trying to do the same thing. Anywhere where I can read up on the basics of what I need to make a DIY rig? Like I said, articles are a little too much for me..


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## NathanB (Jan 21, 2008)

§lipperhead said:


> Easternversant, It seems we are both trying to do the same thing. Anywhere where I can read up on the basics of what I need to make a DIY rig? Like I said, articles are a little too much for me..


If you can wait a month, and drive up to Herdon, va. There will be a diy led workshop hosted by RapidLED & GWAPA. GWAPA • View topic - June Meeting on LED


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## easternversant (Sep 4, 2012)

Sure. There are some basics in my build and one by nonliteral that I based most of my build off of. 

As far as tools, you'd basically just need a soldering iron, solder, and wire strippers. Depending on how you hang it, you may need a drill. If you get a kit from the US (somewhere like rapidled) then everything else is pretty much included. I've never done anything electrical before in my life, if you exclude being electrocuted repeatedly in the third world, and I feel comfortable leaving my apartment without worrying about it burning to the ground. Seriously, who makes electrically heated showers with exposed wires?!?!

I'll work on finishing my build thread over the weekend. Feel free to pm me...

PS. I'm no expert.


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## slipperheads (Oct 17, 2007)

NathanB said:


> If you can wait a month, and drive up to Herdon, va. There will be a diy led workshop hosted by RapidLED & GWAPA. GWAPA • View topic - June Meeting on LED


Thanks, Nathan! I am definitely interested in that because I am moving to northern Virginia in a couple weeks.


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## slipperheads (Oct 17, 2007)

easternversant said:


> Sure. There are some basics in my build and one by nonliteral that I based most of my build off of.
> 
> As far as tools, you'd basically just need a soldering iron, solder, and wire strippers. Depending on how you hang it, you may need a drill. If you get a kit from the US (somewhere like rapidled) then everything else is pretty much included. I've never done anything electrical before in my life, if you exclude being electrocuted repeatedly in the third world, and I feel comfortable leaving my apartment without worrying about it burning to the ground. Seriously, who makes electrically heated showers with exposed wires?!?!
> 
> ...


Funny, I tried to see that tutorial but the link was broken or something, and your link to the page worked. Thanks for that. I guess for my situation, DIY is the way to go.


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## NathanB (Jan 21, 2008)

I'm a big fan of Inventronics drivers, especially for people new to diy electronics (ledgroupbuy.com) They are much easier to use dimming wise than the meanwells if you're not using a controller.


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## slipperheads (Oct 17, 2007)

Nathan, how do I calculate the correct driver(s) I need for my LED's I choose? I assume you combine the wattage's of each LED and find a driver that has the capacity for it?

Will


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## NathanB (Jan 21, 2008)

no, forget about watts. With leds its about voltage and amperage.
Heres a good post explaining it
http://www.dendroboard.com/forum/parts-construction/93649-need-led-lighting-help.html#post844611

Personally I just told the vender (ledgroupbuy.com) how many leds I wanted to run and they gave me the driver options. Thats the good thing about using one of the hobby oriented US companies (ledgroupbuy.com, Stevesleds.com, rapidled.com etc). They will walk you through everything


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## easternversant (Sep 4, 2012)

NathanB said:


> no, forget about watts. With leds its about voltage and amperage.
> Heres a good post explaining it
> http://www.dendroboard.com/forum/parts-construction/93649-need-led-lighting-help.html#post844611
> 
> Personally I just told the vender (ledgroupbuy.com) how many leds I wanted to run and they gave me the driver options. Thats the good thing about using one of the hobby oriented US companies (ledgroupbuy.com, Stevesleds.com, rapidled.com etc). They will walk you through everything


You can also just look at the maximum amperage the leds you are getting can run at, then get a driver with a max slightly below that. So if your LEDs can run at 1500 mA (which you shouldn't because you'll reduce their life) then maybe get a driver that can do 1300 mA. If you are going to be running multiple strings in parallel off the same driver, then get something that can do more, because you are effectively cutting your amperage in half by running in parallel.


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## NathanB (Jan 21, 2008)

If you're using a proper heatsink there is no problem running them at the max, you just need to keep them from getting to hot.


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## slipperheads (Oct 17, 2007)

Since the tutorial is in parallel I most likely will do the same. It is also good for when a diode blows out or something.


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## NathanB (Jan 21, 2008)

All mine are parallel, had one of the older model leds blow without any issues. They used to recommend using a fuse, but I noticed that the big places are not selling them so that may be unnecessary now.


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## TerraFerma (Feb 20, 2011)

§lipperhead said:


> Since the tutorial is in parallel I most likely will do the same. It is also good for when a diode blows out or something.


If you don't want to mess about with soldering - Rapid LED sells solderless (they connect with little wire harnesses) LED's that don't cost much more than the regular emitter on a start. They are very, very easy to setup.


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## usctom (Mar 30, 2013)

For the same amount or less you could get a premade one from reefbreeders. You can get a custom color for $180. You would need 2 of them.


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## skanderson (Aug 25, 2011)

one of the guys on Theplantedtank site sells a combo driver and controller. it will run 4 strings of leds and be able to turn them on and off and also dim each string individually. they are very cool and easy to use. i used it on my last build and it was alot easier than the previous 2.


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## slipperheads (Oct 17, 2007)

skanderson said:


> one of the guys on Theplantedtank site sells a combo driver and controller. it will run 4 strings of leds and be able to turn them on and off and also dim each string individually. they are very cool and easy to use. i used it on my last build and it was alot easier than the previous 2.


Would that be this?:
A Cheap, Simple, Compact DIY LED Controller/Driver COMBO.

Seems a little confusing me :/

I have been reading up a bit on _how many_ LEDs to run for a setup like mine, everywhere from 24 to hundreds. What do you guys think would be a good fit, assuming the LEDs had optical cones? Remember, this sucker is FOUR and a HALF feet HIGH! I am looking for penetration over anything, so I assume that the number of LEDs depends on the amount wattage I get out of each one to cover the floor space. 

According to this article (below), the answer to that is about 40. But I am skeptical because equations never cover everyone's special needs.

http://playsofrays.blogspot.in/2012/12/leds-made-easy.html

THe equation he used:


> How Many LEDs to use for my tank?
> When building a LED light unit for your tank, the first question comes to your mind is- how many LEDs to use. The rule of thumb says-
> 
> Numbers of LED to use = The area of footprint of your tank / 22.
> ...


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## Dendro Dave (Aug 2, 2005)

Have you just considered getting some incandescent strip lights, or zoomed/exoterra strips and loading them up with 13watt jungle dawns from Lightyourreptiles.com? Fairly inexpensive compared to most of the other good LED fixtures, and much less hassle then DIY....

I'm loving the sample jungle dawns and led bar Todd sent me for the dryad FX viv. The mix of different color leds in each bulb make for a smooth blend of lighting with better color rendering and plant spectrums then you get with typical 6500K cfl/t-5/led's

They all point down too... so pretty good penetration, and very bright...probably 1.5-2x as bright as cfl's of similar or even almost double wattage. I swear the 13watt is twice as bright as 26 watt 6500k cfl...but hey it is all pointing straight at you instead of going around a bulb where roughly half the light is in the wrong direction without good reflectors.

The samples sold me...I'll be converting most all my vivs to them over time.


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## slipperheads (Oct 17, 2007)

Dendro Dave said:


> Have you just considered getting some incandescent strip lights, or zoomed/exoterra strips and loading them up with 13watt jungle dawns from Lightyourreptiles.com? Fairly inexpensive compared to most of the other good LED fixtures, and much less hassle then DIY....
> 
> I'm loving the sample jungle dawns and led bar Todd sent me for the dryad FX viv. The mix of different color leds in each bulb make for a smooth blend of lighting with better color rendering and plant spectrums then you get with typical 6500K cfl/t-5/led's
> 
> ...


Are you suggesting buying up the terrarium hoods and packing each with a jungle dawn LED light?

But does it really penetrate down to the bottom as well as an array of 3W LEDs? Going four feet wide, that would be a lot of fixtures to rig up in order to match up to the level of illumination a 3W LED array can bring to the table. Perhaps more costly. But maybe I am wrong? I'm here to learn .


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## usctom (Mar 30, 2013)

§lipperhead said:


> Are you suggesting buying up the terrarium hoods and packing each with a jungle dawn LED light?
> 
> But does it really penetrate down to the bottom as well as an array of 3W LEDs? Going four feet wide, that would be a lot of fixtures to rig up in order to match up to the level of illumination a 3W LED array can bring to the table. Perhaps more costly. But maybe I am wrong? I'm here to learn .


I don't think they would penetrate that far without lenses.


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## Dendro Dave (Aug 2, 2005)

§lipperhead said:


> Are you suggesting buying up the terrarium hoods and packing each with a jungle dawn LED light?
> 
> But does it really penetrate down to the bottom as well as an array of 3W LEDs? Going four feet wide, that would be a lot of fixtures to rig up in order to match up to the level of illumination a 3W LED array can bring to the table. Perhaps more costly. But maybe I am wrong? I'm here to learn .


First I looked at those 2 lights you mentioned in your original post...

That led bar is 180 lumens...the light reflecting off my face from this computer screen is probably brighter then that....I put over 1000 lumens on a 10gal...and while lumens only correspond to visible light and don't mean to much for plants, since we are using daylight spectrum lighting basically it works out that if the tank looks bright enough for plants...it probably is...if it looks kinda dim...then it probably is...its not a hard/fast rule but just another general guideline like the wattage per gallon guidelines.

The 5050 strip lights, firstly are overpriced...you can get rolls that long for much cheaper on ebay....second you would basically have to cover then entire surface area of your tank top with those to maybe have a chance at getting adequate light...basically wallpaper the tank in them...

I don't know after doing the calculations later in this post (I came back to this section for some edits) that may actually be the cheapest way to go...I'm just not sure there is enough lid surface area to accommodate enough of those leds...and it will basically black out the lid and prevent you from using more lights on top to supplement that.

Anyways I was Essentially going to say yes (another edit) but after figuring it up later in this post I don't think it would be feasible. I think your basically going to have to go for at least 1 or 2 large fixtures that use a crap ton of 3watt led bulbs.

If you don't go DIY, and franky I wouldn't on such a large build if you've never done it before unless you are very technically inclined (cut your teeth on a smaller diy led build first) You're looking at basically using high end expensive freshwater or reef lighting, or a bunch of cheaper fixtures with jungle dawns or something. Elegance vs brute force, but likely a combination of both will be the cheapest short of a clever diy solution... 

So the best option is probably to go with a big fixture that comes with a lot of 3watt leds and lenses, then use a couple of cheaper incandescent fixtures with jungle dawns behind that big strip to fill out the light...that may save you the cost of buying a 2nd or at least a 3rd high end led fixture when it might not be necessary.

I think some have said not to be concerned with wattage, I only scanned the other responses so If this is out of context I apologize, but I'm going to kinda disagree...wattage can be an easy way to figure out how much light you need...ball park at least. Typically most standard vivariums up to the height of a 55 or 75 gallon can be well lit with somewhere between 2-4watts of cfl/t5 lighting per gallon...but with Leds you can usually get away with 50-75% of that wattage because they are just naturally more focused with better penetration and generally all pointing in the direction you want the light to go.

But you are building a tank more then twice the height of a standard 55-75 gallon, but of similar front to back depth, so if you were going with cfl or t-5 lighting you'd probably need in the neighborhood of 7-10 watts per gallon...with led's being more focused, especially ones using lenses you may be able to get away with (I'll error on the side of caution here, and say...) 4-7 watts of led lighting per gallon to be sure you've got really good light for good plant growth all the way down to the bottom. 

The cheapest 48" long Led fixture that I can find on ebay that that uses 3watt leds and has enough of them to put a dent in the amount of required lighting for this tank has 192 watts of led lighting using 64 3watt leds....

Your tank if I used the formula right is just under 195 gallons...so if we basically double the typical 2-4 watts per gallon *general guideline* for most standard aquariums comes to lets say 8 watts per gallon, but your tank is so tall you probably wanna tack on 1-2 more watts per gallons...so lets be safe and say 10watts per gallon of standard cfl/t-5 lighting but you are using leds which tend to penetrate better and all be pointed in the down direction so lets cut that by (guesstimating here) lets say 5 watts which leaves us at probably needing 5 watts of led lighting per gallon of tank for a tank this tall (This is for really good lighting, not just adequate or fair)...give or take a watt either way....5 x 195 gallons = 975 watts of lighting  (I have 100watts just over a 30 cube and its still difficult to grow plants in the tannin stained pond area).

Lets say I've way over estimated here...and cut the requirement down to basically double what the watts per gallon for most standard tanks would be with leds (1-2 watts...average it to 1.5 watts per gallon).

So now we are down to 3watts (remember we doubled our led wattage requirement because of tank height) of led lighting per gallon in the hopes that will be enough for a viv this tall and 195 gallons, 192 watts of lighting per 245 dollar fixture...so your looking at $$735 (not including any shipping charges/taxes) worth of the cheapest 3watt bulb led fixtures I can find anywhere to get 3 watts of lighting per gallon on a tank more then twice as tall as most any standard aquariums up to 75 gallons. 

With the lenses and some luck relying on leds better focused light you may find 2.5-3 watts per gallon is adequate (Or else you will have to go with very low light plants on the floor probably)...but probably not much less then that or your tank will be really dim at the floor. So maybe you could get by with 2 of those cheapest 3watt bulb led off brand china made fixtures...but your still looking at $500 for 2...and you may find that really you need 3...so $735.

Compared to the cheapest led off brand china fixtures I can find it would be more expensive to go with all jungle dawns in incandescent fixtures for the entire lighting setup..and probably not feasible due to the number of bulbs/fixtures you'd need. I should have paid more attention to your tank dimensions before I said that but I just kinda jumped in assuming we were talking about more standard sizes like usual...my bad. 

But the jungle dawn/incandescent combos might be really useful for filling out your main lighting scheme, at the very least you may find you have to use some cfl or t-5 lighting to save money and fill out the light requirements...the jungle dawns are a relatively cheap way of doing that compared to other led fixtures and very good because of the mixed color temps. So not quite the cheapest way to go to fill out your light requirements but a cost effective way that gives you very good quality light in plant spectrum and color reproduction.... and remember the costs that I quoted on these large 3watt 48" fixtures are for off brand China stuff that a lot of people feel is questionable safety wise (though I think they have gotten better over the last few years from what I hear)...Honestly I might risk it for those prices but it is definitely something to consider especially when you will probably need at least 2 if not 3 or 4 of them...that is more chances at failure...and the name brand more well known stuff is considerably more expensive for the same amount of lighting, though may be safer.

The cost does make the diy solutions attractive...you could buy 10 +watt crees or something build your own light bar/heat sink setup and then find the right drivers/ballasts but there is a definite learning curve there. I've never done it some I'm going to try to avoid it.

Anyways basically it isn't going to be cheap...and the cheapest ways are probably going to be the the hardest to do (Diy). I'm in the same boat though because basically your tank dimensions are similar to what I'm planning on for my Dryad FX vivarium build. 

Todd's donation put a good dent in my lighting needs, but I'll probably have to use several of my old fixtures or even end up stealing fixtures off other vivariums to meet my lighting needs at least initially because I won't be able to afford $500+ in lighting after paying to build this viv from scratch...at least not for awhile  

I don't know though, I've never tried to actually light something this tall and that led bar he makes is awesome and so are the jungle dawns compared to the cfl lighting I usually use... So maybe I'll get lucky and find that bar coupled with a few fixtures full of jungle dawns is adequate enough. So basically all I can do is give you my thinking/methodology that I find works on tanks half this height or less...and basically double it. A 55 is short enough that a couple 4ft shop lights might work well enough...but on a tank this tall that just isn't going to cut it. 

Best of luck! ...hope some of my ramblings prove useful! Hurry up, I wanna see how it goes so I can get a better since of how to light my own really large viv!


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## Dendro Dave (Aug 2, 2005)

usctom said:


> I don't think they would penetrate that far without lenses.


Enough of them would, light just doesn't stop at a certain point...but after calculating how many you'd need you probably wouldn't have the room for enough fixtures to hold enough bulbs...so basically they are a good choice for supplementing your main lighting on a tank this large but probably can't serve as the focus...now a few of Todd's led bars might work...but I'm not sure he has many left or is going to continue to make them.


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## skanderson (Aug 25, 2011)

that is the right unit. i have 2 and they work well for 3 watt leds. over the bump out in my big viv i have 24 cree xlms running at 2 amps with 30 degree optics. the lights are a bit over 5 feet over the floor of the viv and supply 100 par at that distance. this give me good color and the ability to grow things on the floor like cephalotus.


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## skanderson (Aug 25, 2011)

i would also think that without lenses any leds will not give great par at the floor. too much will be lost through the glass in the front for example. in the area i have lit the volume is close to 200 gallons, 2 feetx 3 feet x 5 feet x 7.= 225 gallons approximately. i think volume is a good way to calculate lighting need as if takes into consideration all 3 dimensions. my 24 led xml light gives great intensity, 100 par at the floor, for a total wattage of 168 watts plus a bit more for the fan and for the drivers inefficiencies. that leds for that unit were around 6or 7 bucks apiece and the heatsinks and drivers added about another 200 for a total of somewhere around 350 dollars. this is for a very efficient unit. if you went with more numbers of cheaper emitters you could get that price lower im sure. for my next build i am planning on using the new rebels m that are now just coming out. im waiting on a source of mounted leds and i need to check the pricing as well. i used cree xml u2s for cool white and cree xml t5 for warm white. if you wanted to push it even higher in efficiency you could get the new xml2 u2 which are even more efficient. also cree is coming out with a new emitter that is also very efficient but at a better color temp for out uses. dont be discouraged i am good with my hands but definately not a tech guy. ask any questions you want . one more thing is that the cree website has a tool that you can plug in different leds and it will give you the all the specs as a spreadsheet.


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## TerraFerma (Feb 20, 2011)

§lipperhead said:


> Are you suggesting buying up the terrarium hoods and packing each with a jungle dawn LED light?
> 
> But does it really penetrate down to the bottom as well as an array of 3W LEDs? Going four feet wide, that would be a lot of fixtures to rig up in order to match up to the level of illumination a 3W LED array can bring to the table. Perhaps more costly. But maybe I am wrong? I'm here to learn .


What kind of plant life are you trying to get going on the floor of your tank? If you want to grow moss the CREE XM-L's and perhaps Phillips Luxeon M's (I haven't tried the M's yet but they look good) are you what you will need. The issue is - they are a VERY bright point source when run above even 1/3 power. This is good for punching light to the bottom of your tank but can be troublesome for any plants in the top 2 feet of the viv. I run 16 XM-L's on a 24" x 18" x 24" Exo - I run them wel below 50%. And they still roast things on the bottom of the tank. 

Lenses can help focus something like the XP-G's but then you are going to potentially need more of them. I'm moving away from XM-L's to fixtures with a bunch of XP-G's as I'm tired of roasting plants. Could run a bunch of XM-L's on low but then it kind of defeats the purpose of paying up for the XM-L's. If you want to get tricky you could run XM-L's with lenses on the front of the tank only and then lesser stuff on the middle/back of the tank where the background will presumably have stuff up higher in the viv.


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## slipperheads (Oct 17, 2007)

TerraFerma said:


> What kind of plant life are you trying to get going on the floor of your tank? If you want to grow moss the CREE XM-L's and perhaps Phillips Luxeon M's (I haven't tried the M's yet but they look good) are you what you will need. The issue is - they are a VERY bright point source when run above even 1/3 power. This is good for punching light to the bottom of your tank but can be troublesome for any plants in the top 2 feet of the viv. I run 16 XM-L's on a 24" x 18" x 24" Exo - I run them wel below 50%. And they still roast things on the bottom of the tank.
> 
> Lenses can help focus something like the XP-G's but then you are going to potentially need more of them. I'm moving away from XM-L's to fixtures with a bunch of XP-G's as I'm tired of roasting plants. Could run a bunch of XM-L's on low but then it kind of defeats the purpose of paying up for the XM-L's. If you want to get tricky you could run XM-L's with lenses on the front of the tank only and then lesser stuff on the middle/back of the tank where the background will presumably have stuff up higher in the viv.



GReat points, and thank you to everyone who has posted large comments to share their brainpower! 

I am mapping out what I think this lighting system will look like. I will post up something soon, maybe a drawing, with a list of products i'm thinking of.

Thanks again


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## Dendro Dave (Aug 2, 2005)

Another option I'm not sure anyone has brought up is you could use downward facing incandescent fixtures and put large led spot lights in them...basically run a series of these across the front of the tank so the light punches down to the floor then run other fixtures along the back to fill out the lighting, take care of any spot lighting effect and keep the light soft enough near the top/back of the viv so you are less likely to burn plants in the upper portions. Not sure what the cost would be...you could use cheap desk lamp type fixtures, but large led spots are still kinda pricey and you'd probably need 6-10 of them? (just guessing here), plus whatever fixtures you used to fill out the lighting


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## slipperheads (Oct 17, 2007)

This is something I have been looking at for a while now for reference, but he never put up any information on lighting. His tank is 4' x 2' x 5'... VERY close to me.

http://www.dendroboard.com/forum/parts-construction/82079-large-terrarium-build-4.html

And here it is in action:








You see the lighting at the bottom of the page show up in pictures but he didnt talk about it. I am going to try to get him into the thread.

EDIT I Guess I should have gone back to read through the entire thread:


> Photo is with 2 x 96watt pcf bulbs going. I'd like to wire them up separately and have one kick on in the morning, then the other at noon- have a few hours of overlap, and then the first light kicks off. It'll give some indication of day length/change.
> 
> Another thought is to try out some of these LED bars people seem to be enjoying...


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## rabu92 (Mar 9, 2013)

I'm going to try to spew out a good chunk of LED knowledge in one post 
I hope it won’t be too much to take in but given that the article you linked had some advanced topics I‘m guessing this won’t be a problem.

Before I start, the result of the following calculations is this: 10.000 lumens with 60 degree lenses.
This is a big number which I due to the height of the tank. But it is feasible.

*TOP TIP:* put all the following equations in excel so that you can easily change numbers and get a result instantly.


*Lumen vs Wattage:*
First things first, it's not so much the wattage that counts, it's the lumen output. This is because all LED's have different Lumen/Watt ratings. 
For example the new Cree XM-L2 T6 produce 318 lumen @ 700mA, while the older Cree XP-G R5 produce 260 lumen @ 700mA. That may seem like a small difference but multiply that by 24 LED's and that becomes a whopping 1392 lumen difference.​
To calculate the needed amount of light you will have to know how much usable light the LED produces. These next few concepts will help in calculating this.

*PPF (photosynthetic photon flux):*
PPF is a number that will tell you how many photons (= light particles) the LED produces which plants can use for growth, hence the name photosynthetic photon flux.
An easy but fairly accurate way to convert lumen to PPF for LED's is this: Lumen/72.
Unit = micromoles/second (micro = 0,000001)

PPF tells you how many photons are produced but it doesn't take into account how much space they have to cover. This is where PPFD comes in. 

*PPFD (photosynthetic photon flux density):*
So PPFD tells you how many photons per square meter a given point in space is getting. PPFD = PPF/Lit Area in meters squared.
Unit = micromoles/second/m2

Note: PPFD is similar to PAR (photosynthetic active radiation) which more commonly used.

*DLI (daily light integral):*
This measures the amount of photons a plant absorbs throughout the day. 
The formula is this: DLI = PPFD*60*60*x/1.000.000 
*60*60*x converts seconds to days with x the number of hours your lights are on each day
/1.000.000 converts micromoles to moles​Unit = moles/day/m2

*To Summarize with an example:*
An LED produces 1000 lumen with a beam that covers 2 square meters for 12 hours a day:
Lumen = 1000
PPF = 1000/72 = 13,88 micromoles/second
PPFD = 13,88/2 = 6,94 micromoles/second/m2
DLI = 6,94*60*60*12/1000000 = 0,3 moles/day/m2​
You may be wondering what the $*@! do I need all this for?? Well here it is: DLI requirements for plants (page 5 and 6)
When you look at the species you can see Bromeliads require between 4-14 DLI, ferns 2-10, orchids 2-10 ...

The amount of DLI you will need for good plant growth is well... up for debate. It depends on how you define "good growth", for some it is an explosion of growth or for others it's simply sustaining the plant without letting it die. 
But let's say we want to achieve 3 DLI which will most likely be enough for our purposes, after all we're not trying to grow these plants commercially... I think 



Now lets reverse engineer our way back from 3DLI to the needed lumens. That way we'll know how many LED's you'll need.

*Calculating the surface area:*
The LED's will have lenses. They focus the light into a beam with an angle. The area the beam will cover is a circle with a radius. That radius depends on 2 things: Height of the LED and Angle of the beam.
Formulas: 
Radius = Height*Tan(Angle/2)
Area = Pi*Radius^2
*To Summarize with your tank's dimensions:*
Your tank is 4,5 feet high... that's big 
Let's say the angle of the lens is 60 degrees.
Radius = 4,5*Tan(60/2) = 2,6 feet
Area = 3,14*2,6^2 = 21,2 square feet
Area in meters squared: 21,2*0,0929 = 2 square meters​
*Getting back to lumens:*
DLI = 3
PPFD = 3*1.000.000/60/60/12 = 69,4 (with the article you linked this means high light: PAR>50)
PPF = 69,4*2 = 138,8
Lumen = 138,8*72 = about 10.000

As you can tell that's a BIG number, 10.000 lumens.

With Cree XM-L2 T6's driven @ 2500mA which will produce 770lumens you would need 13 of them. Which would be 13*8,1Watt = 105Watt
With Cree XP-G R5's driven @ 1300mA which would produce 420lumens you would need 24 of them. Which would be 24*4,2W = 100Watt


*Some things to remember when setting this up:*
The intensity of the light will go up exponentially when you get closer to the LED. So when the bottom will receive 3 DLI, the plant's half way up in your tank would be getting 12 DLI and those 1 foot from the top would be getting a murdering 60 DLI. To give a meaning to that insane number, an area in full midday sunlight gets a max of 60 DLI. Most tropical plants will die with more than 20-30 DLI.
This means that you should be careful when planting this monster because you could easily burn your plants to death.

Another downside with such a big tank is that you have to use those 45-60 degree lenses to punch the light to the bottom. This means that the top area of the tank will a) be mostly black areas because of that small beam angle and b) the areas that are lit will be getting way too much light.
To solve this you will a) need to put extra lights on top with a wide beam angle to provide light to the dark areas and b) make sure you don't plant anything in the bright areas.


*This is how I plan to build my tall tank:*
I'm doing a similar build to yours, although not as extreme. My tank will be just under 4 feet high. I have solved the bright/dark problems by dividing 15 Cree XM-L2 T6 LED's over 5 heatsinks. 2 with 60 degree lenses pointing to the back wall, 2 with 60 degree lenses pointing to the bottom/rear and 1 with 30*60 lenses (ellipse) pointing to the bottom. Each heatsink has 3 LED's.

Here is the my design:

















Basically what I did, was made sure the lights don't overlap as much on top but overlap a lot near the bottom. Also where the lights overlap on top I made sure I wasn't going to plant anything. It toke a while to figure out but I'm confident this will work.


Here are the DLI numbers depending on the distance from the top of the tank (with the setup and angles from the pictures above): It is running 15 Cree XM-L2 T6 @ 1,8Amps
With this design you would be getting about 2 DLI @ 1,8Amps on the bottom of your 4,5 foot tank.










Anyway I hope this made things more clear and I apologize if I toke over this thread


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## slipperheads (Oct 17, 2007)

Wow. Thanks a lot for the visuals and technical information. I think I understood most everything that was explained.

How do you plan on rigging up all those heatsinks in the various angles like that?


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## rabu92 (Mar 9, 2013)

I'm going to attach 2 steel bars across the light box. Then I will hang the individual heatsinks on those 2 bars with 4 strings. Each string can be adjusted in length thus giving me full control of tilt and shift of the heatsinks.
And the steel bars will be removable so that I can lift the whole lighting fixture out of the tank without disconnecting everything.

Visuals always do the trick don't they  It was pure luck my tank has roughly the same dimensions 


Btw my exams will be starting soon so if you have any further questions it might take a while before I can read/answer them. I will be spending most of my time reading chemistry books instead dendroboard threads


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## skanderson (Aug 25, 2011)

i just found this thread after looking at your build thread. what color temp crees are you going to be using. also if they are done do you like the color? thanks, steve


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## myersboy6 (Aug 23, 2010)

Wow this was an awesome read but I do not understand stand it all. Haha This is what I've been looking for though cause my broms just aren't getting the right color anymore to them and I'm not quite sure why cause they were okay for a long time and now they have all pretty much lost there color and my moss is turning yellow on the ends... I will have to reread to try and retain some more information. I'd really like to build my own led fixture. I'm tired of buying lights that just don't quite work the way they should.


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