DIY LEDs - The write-up

[widmer]

They are for adding shimmer to a tank that will have 4 T5HO(54W).

The Cree XP-G will do the best job for you. It can produce the most light from a single point source, and that is the key to shimmer. If your only goal is shimmer my guess would be four (or maybe fewer even?) of these driven at 1000 mAh. This could be acheived with a $15 buck puck and the right wall wart/old laptop charger.

 

[S.B.D.]

What would you say about a fragtank?
47½L 10H 12D...
Currently running 39wx6 T5 with mainly SPS and some LPS.
What kind of wattage are we talking about to get similar PAR/growth?
I have allso had some problems figuring out how high the leds should be from the water and whit what kind of lenses(angle) for optimum spread/effect?
I would not mind having the led´s some distance from the water in order to get better access to the tank.

Most grateful for any help with my coral nursery uppgrade.

 

[Eltonka]

The Cree XP-G will do the best job for you. It can produce the most light from a single point source, and that is the key to shimmer. If your only goal is shimmer my guess would be four (or maybe fewer even?) of these driven at 1000 mAh. This could be acheived with a $15 buck puck and the right wall wart/old laptop charger.

I forgot about the xp-g. Ill look into those. I was going to run them at 700mA, do you still think 4 would be enough for 55gal tank? Its 4ft long. I was
thinking of maybe going with 5.

Thanks for the info, Im just gonna try one and move forward.

 

[der_wille_zur_macht]

If you're going to use a buckpuck, you might as well get 6. With only 4 or 5 spread over a 4' tank, you might get a bit of "spotlighting" that you may or may not want.

 

[der_wille_zur_macht]

What would you say about a fragtank?
47½L 10H 12D...
Currently running 39wx6 T5 with mainly SPS and some LPS.
What kind of wattage are we talking about to get similar PAR/growth?
I have allso had some problems figuring out how high the leds should be from the water and whit what kind of lenses(angle) for optimum spread/effect?
I would not mind having the led´s some distance from the water in order to get better access to the tank.

Most grateful for any help with my coral nursery uppgrade.

Most people who have converted end up with 1/3 - 1/2 the wattage of LEDs compared to T5, for similar results, assuming you're using "best of breed" HP LEDs.

Mounting height and optics - pick your desired height, then use optics to match. Your tank is shallow, so you can stay a bit wider than some might use. 8 - 10 inches, no optics. 14 - 18 inches, wide (60 - 80 degrees). 18 - 24 inches, medium (40 degrees). Above 24 inches, talk to widmer.

As with any build, it might make sense to get a few different optics and test to see what you like.

 

[shizno]

Are those guidelines based on the tank depth or from bottom of tank to whereever the led fixture is hung?

 

[XSiVE]

Are those guidelines based on the tank depth or from bottom of tank to whereever the led fixture is hung?

typically those guidelines are from water surface / top of the tank.

 

[BigFloppy]

typically those guidelines are from water surface / top of the tank.

3" or 4" above tank is potimal for LED's
If you want to hang higher than that, expect to narrow the beam width of the optics, I'm running 45 degree optics underdriving 3W led's on 2" centers

I'm getting acceptable light out of a 5x4 matrix on a 29G nano system... 280-300 PAR a bottom of the tank, led's are 3" off surface of the water

 

[laverda]

Just in case any one was looking for extrusions these are designed for LEDs and have lenses. http://www.led-tech.de/en/High-Power-Supply-c_106_0.html I thought they looked very interesting and may order some.

 

[XSiVE]

3" or 4" above tank is potimal for LED's
If you want to hang higher than that, expect to narrow the beam width of the optics, I'm running 45 degree optics underdriving 3W led's on 2" centers

I'm getting acceptable light out of a 5x4 matrix on a 29G nano system... 280-300 PAR a bottom of the tank, led's are 3" off surface of the water

It really depends on too many variables, as well as personal preference to say what is optimal for everyone. I have my LEDs 12-13" above the water, with wider optics than you, but they are spaced further apart to provide more coverage, yet I get right about the same PAR values at the same depths as you have... :crazy1: so like I said, too many things to consider to give such a small range and say what's optimal. What works for you would not work in a large footprint tank such as mine.

 

[longiotti]

quick question LED help please

quick question LED help please

I do not want to highjack this at all just have a question that you LED experts could help me with.
I went a different route. I am using the smaller 10MM leds and they work great but they dim and burn out after about 3 months. my corals love them and the lack of algee on the glass and low electric bill has me loving these leds.
quick rundown
running 252 whites
http://cgi.ebay.com/20-PCS-10mm-40-0-5W-5-Chips-White-LED-100mA-290000mcd-/370196936041?pt=LH_DefaultDomain_0&hash=item563174f569#ht_3973wt_911

running 252 blues
http://cgi.ebay.com/20-PCS-10mm-40-0-5W-5-Chips-Blue-LED-100mA-170-000mcd-/330459936164?pt=LH_DefaultDomain_0&hash=item4cf0f275a4#ht_3717wt_911

I am running these 3 in series with a 39 Ohm resister.
I have cooling fans running in the hood with them to keep them cool

LED specs
.5 V fowarding voltage
100Ma
3.4 running voltage

I was just running a 12 volt power supply.
It was variable and I had it tunned way down even down to 11 volts for the blues and they still dimmed
the more I have been reading I may need an LED driver
any help and suggestions on what I should use would be great.
thank you
Lance L

 

[der_wille_zur_macht]

You need LEDs that can handle the intensities we need on fish tanks. Putting a driver will only allow you to choose the current you're running at, which you're doing now via current limit resistors, so it won't allow the LEDs to last any longer, if that's the problem you're trying to solve.

 

[XSiVE]

I do not want to highjack this at all just have a question that you LED experts could help me with.
I went a different route. I am using the smaller 10MM leds and they work great but they dim and burn out after about 3 months. my corals love them and the lack of algee on the glass and low electric bill has me loving these leds.
quick rundown
running 252 whites
http://cgi.ebay.com/20-PCS-10mm-40-0-5W-5-Chips-White-LED-100mA-290000mcd-/370196936041?pt=LH_DefaultDomain_0&hash=item563174f569#ht_3973wt_911

running 252 blues
http://cgi.ebay.com/20-PCS-10mm-40-0-5W-5-Chips-Blue-LED-100mA-170-000mcd-/330459936164?pt=LH_DefaultDomain_0&hash=item4cf0f275a4#ht_3717wt_911

I am running these 3 in series with a 39 Ohm resister.
I have cooling fans running in the hood with them to keep them cool

LED specs
.5 V fowarding voltage
100Ma
3.4 running voltage

I was just running a 12 volt power supply.
It was variable and I had it tunned way down even down to 11 volts for the blues and they still dimmed
the more I have been reading I may need an LED driver
any help and suggestions on what I should use would be great.
thank you
Lance L

Did you test the amount of current draw that each string is getting? You will want to check this to help diagnose the problem.

It seems like you're missing two key elements. One is some sort of constant-current driver for your LED strings, another is a way to properly get the heat away from the LEDs. A simple fan with no real heatsink may not be enough to keep them properly cooled.

 

[der_wille_zur_macht]

It seems like you're missing two key elements. One is some sort of constant-current driver for your LED strings, another is a way to properly get the heat away from the LEDs. A simple fan with no real heatsink may not be enough to keep them properly cooled.

Half right - the resistors he's got essentially are the constant current driver. There's nothing wrong with this approach if you don't mind the lack of (programmatic) dimming, potential for low efficiency, and potential for variability.

Thermal management is what's killing these LEDs. They're just standard gumdrops in a plastic package, so there's really no way to "heatsink" them with any effectiveness. The only real way to use these longterm is to run them at a lower current, and at that point you're buying enough of them that it would be more expensive than just buying the proper number of HP LEDs to begin with!

 

[XSiVE]

Half right - the resistors he's got essentially are the constant current driver. There's nothing wrong with this approach if you don't mind the lack of (programmatic) dimming, potential for low efficiency, and potential for variability.

Thermal management is what's killing these LEDs. They're just standard gumdrops in a plastic package, so there's really no way to "heatsink" them with any effectiveness. The only real way to use these longterm is to run them at a lower current, and at that point you're buying enough of them that it would be more expensive than just buying the proper number of HP LEDs to begin with!

Yeah I must have missed the part where he said he had resistors in line. It would definitely be good to know how much current is flowing through those LEDs. Im guessing the 100mA is the rated max, just like on most of the high powered LEDs, 1A or 1.5A rated max, but most of us do not run them at those high currents.

 

[lokian]

im thinking about a DIY led setup for a 8' x 2' x 2'... how many leds would i need for a setup like this to keep clams and most corals?

 

[shizno]

Found another oooold multimeter laying around, only it reads DC volts, AC volts and resistance....is there any way I can use this to calculate/adjust the meanwells?

 

[kcress]

Didn't I just explain it to you? Using a resistor?

 

[westmoorenerd]

Lokian, 192-240 should work for that size tank, maybe even less....That's what I'm going with on my 8'x3'x3', whenever I get all my LEDs in...

 

[der_wille_zur_macht]

LED count on large tanks is open for a fair amount of subjectivity. On my 360g I'm planning on far fewer LEDs than the "rules of thumb" would suggest, since I'm not lighting open sand, the overflow box, or other areas without corals nearly as intensely.