LED basics

digidana

digidana

Member
can anybody point me in the direction of some good general info on LED lighting? i just bought jarred's cube and would like to put the equivalent of a 400w MH on it. thanks!
 
You should ask Jarrett about it, if you can. He's EXTREMELY knowledgable about LEDs.

I think Scott knows a bunch about it by now too though.
 
Check out my post on the club website where I wrote up my DIY LED build. It might help. And I link to a lot of information on the subject.

If you have specific questions, though, I am sure that I can help out. Give me a call or drop me a PM.
 
thanks scott! that's very cool! very nice job. unfortunately i'm not nearly handy enough to tackle a job like that...and i'm in a bit of a hurry. not an emergency yet, but definitely need to figure out something soon.

do you know if there are any fixtures out there that use the super-high efficient LEDs that you found? i know nothing about lumens. how many watts is the typical LED? i'm trying to figure out what size fixture i need for a 30x30x24tall tank. i'd appreciate any help!

thanks!
 
I know there are a few complete fixtures out there that are good for reef tanks, but they are expensive. I'd imagine their numbers are increasing daily, but there is so much variability it is hard to compare them.

I do not really know much about the factory-assembled fixtures. The 3W Crees (XP-G) that I used are among the most efficient ones available (with about 140 lumens per watt at 350 mA and with PAR far exceeding their lumen output). Most of the packaged LEDs I've seen use the 1W LEDs and I doubt they are as efficient. While I built my own fixture because it cost less, I also did it because nothing seemed to compared to the efficiency of the Crees that I used. If you want to use something similar, you can get preassembled kits for fitting in a hood at the location where I got my stuff. Based on what has been said in the DIY forum, I'd probably use about four of those to get 400W equivalent. It will set you back almost $1K (about twice what you'd pay DIY with parts from the same site).

EDIT: Here are a couple more links to the product I mentioned above. Perhaps there are other vendors.
 
tangboy said:
So are the LEDs better then MH or is it a personal preference or based on what you're trying to grow?
Click to expand...
Better in the sense they are more efficient (more PAR per Watt). They also have no radiant energy -- all the heat goes off the back and can be gathered in a heat sink and dispersed in the air above (even assisted with a cooling fan). MH is better in that it is a mature technology and you have a good idea about what you are getting. LEDs are all over the board and you do not know what you are getting unless you get the tech sheets on the LEDs from the vendors and compare them (check lumens per watt, color temp, etc. and perhaps search DIY sites for PAR information).

EDIT: MH is also cheaper on initial cost, but LED is much cheaper if you do a life comparison.

digidana said:
scott, what do you think about fixtures like this one: http://www.aquashoponline.com/28-new-generation-maxspect-programmable-aquarium-led-lighting-g2.html

if i went with something like that would i need g2-400-110w, g2-400-160w, g2-800-170w, or g2-800-230w?

is the 400 or 800, the number of actual led lights? i don't know if 110w would be dark in my tank or would it bleach everything out.

i guess i'm so used to thinking in metal halide terms that this just isn't sinking in!
Click to expand...
I do not know anything about the LEDs they are using, but you would want something like two of the g2-400-110w if they are comparable to the Cree LEDs. I think not given that Semi LED has about 2/3 the luminous flux of the Crees. That website does have a Cree page, though, that has the same fixtures but with Cree LEDs (exact ones I used):

http://www.aquashoponline.com/39-cr...ct-programmable-aquarium-led-lighting-g2.html

The 400 or 800 is the length in mm. The xxxW is the wattage. In this case I would look to get two of the G2-400-110W-J. One of the G2-400-160W-J might work, but the profile is simply the same with more lighting. That would just give you a bright spot under the lights and dark spots in front and back of it. LEDs are very focused and their light does not stray much outside the angle of their optics. This is not a problem if you position it where you want the light.

EDIT: Another benefit of DIY is that you can custom locate the lights where you want them (not that I'd do that without reason because a more balanced light is more easily transferrable to other setups or people).

-Scott
 
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Sorry to hijack but on the rapid site with the DIY retro kit it says one needs to purchase optics for the other LEDs also. I undersatnd what optics do etc. but is there a point to them on a small and shallow tank (5.5 gallon)?

Also is a heat sink needed for their kits?

Thanks.
 
KafudaFish said:
Sorry to hijack but on the rapid site with the DIY retro kit it says one needs to purchase optics for the other LEDs also. I undersatnd what optics do etc. but is there a point to them on a small and shallow tank (5.5 gallon)?
Click to expand...
Shallow tanks do not need optics. My tank is 16" deep, but my effective depth (to top of a big block of rock) is about 6" to 10". I decided not to use optics. I would likely have used 80 degree optics for the 16" depth. The more narrow the optics, the deeper the lumens and PAR will "punch" down into the water. Consequentially, the closer you will need to put them to keep from getting a "bar" effect (bars of light and darkness). I believe the Cree XR-E and XP-G have a natural 90 to 110 degree optic built in (90 degrees being light goes up from perpendicular by 45 degrees in each direction).

Also is a heat sink needed for their kits?
Click to expand...
Yes. They do not include them. Honestly, a wide aluminum bar would work for small applications. I think everybody's massive heat sinks are overdone. Less heat means longer life as far as LEDs are concerned, though.


EDIT: Something like this would work very well for a small tank:
http://www.rapidled.com/servlet/the-101/7-LED-PAR38-Bulb/Detail
 
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Thanks Scott. For whatever reason lighting is the one thing I scratch my head over and over.

I was thinking of doing the 6 led kit from there. If I could head to HD or Lowes and get an aluminum bar that would solve the issue. Correct?

I have an old swing arm desk lamp, rectangular head that I kind of want to use vs. a spotlight though I am not against a spotlight since many people like them.

This is for a 5.5 gallon zoa only tank so I don't want the leds 18 inches off the water's surface so not to melt them.

Thanks again.
 
is there a huge difference between what they're calling "high power" and cree? also when they talk about T8, does that just describe the shape of the fixture, the more 'bar' looking ones?
 
KafudaFish said:
I was thinking of doing the 6 led kit from there. If I could head to HD or Lowes and get an aluminum bar that would solve the issue. Correct?
Click to expand...
I think that would be fine for 6 LEDs so long as it is thick enough (around 1/4") and you had some air movement or venting over the top of it. I am not sure what kind of swing-arm you have, but I wouldn't totally enclose the back side of the moutning plate in fixture without venting or you'd cook the LEDs -- or at least shorten their life. Air flow across the back of the heat sink is key to keeping the temp down.

digidana said:
is there a huge difference between what they're calling "high power" and cree? also when they talk about T8, does that just describe the shape of the fixture, the more 'bar' looking ones?
Click to expand...
When they use "high power", it seems to me that they have clustered them closer together and given them narror optics so they project more light down (and deeper) and less to the sides. This is good for a deeper tank, but you'd need more of the LEDs to cover a larger area.

I am not sure where you are looking to see T8 LEDs, but there are several flourescent-looking bulbs on the market that area really LED retrofits. The T8 LEDs are mounted so that you can install them in a flourescent fixture (like the PAR 38 bulbs are created to be installed in an incandescent socket).
 
soooo, i think i may be narrowing it down. what do you think?

i like this one because the timer is programmable, etc. looks like you can choose between bridgelux and cree bulbs. 3 watt bulbs, 60 degree angle, 28" x 10"ish. i'm looking at the K7236-ultra-108w:
http://www.aquashoponline.com/45-ne...ed-lighting-for-saltwater-built-in-timer.html


and this one, i've read some good things about, but its not programmable. its 16"x9". i also wonder if the 50/50 white/blue is too much blue? i haven't read any complaints, but most seem to be about 70% white, 30% blue:
http://www.shop.reeffiltration.com/product.sc?productId=54&categoryId=5

i'm not sure which would be the best for the 30x30x24 dimensions. the reeffiltration one says it covers 30x24 at 8" high...so it looks like it might fall a little short? but i really like the good reviews.
 
digidana said:
i like this one because the timer is programmable, etc. looks like you can choose between bridgelux and cree bulbs. 3 watt bulbs, 60 degree angle, 28" x 10"ish. i'm looking at the K7236-ultra-108w:
http://www.aquashoponline.com/45-ne...ed-lighting-for-saltwater-built-in-timer.html
Click to expand...
Looks like a good one. I would select the Cree version because it is what I know. Note that that fixture only has 36 3W LEDs -- not quite 400W MH equivalent. As for the fixture geometry, I think it is a bit wide. But so long as the light goes over about where your coral are depth-wise, it will be good. Mounting it a little higher would help with that. I like the geometry of two K5518-EX (keeps extra light off the glass), but for the cost I'd probaly go with the one you listed.

and this one, i've read some good things about, but its not programmable. its 16"x9". i also wonder if the 50/50 white/blue is too much blue? i haven't read any complaints, but most seem to be about 70% white, 30% blue:
http://www.shop.clayboa.com/product.sc?productId=54&categoryId=5

i'm not sure which would be the best for the 30x30x24 dimensions. the reeffiltration one says it covers 30x24 at 8" high...so it looks like it might fall a little short? but i really like the good reviews.
Click to expand...
The link is bad so I can not see the second one. As for dimensions, I doubt you want the LEDs up to the edge. You do want it to be deeper to cover your tank. On a cube tank, I think ideally the fixture should be a square. Again, it depends on your coral locations. If you want a free sandy area in front, then these rectangles would be find because you could put the fixture back over the corals. This isn't like a MH fixture that has a lens to cast light forward and back. Light only goes at a few inches around each LED (depending on the focus of the optics).
 
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