DIY LED Build for 20 Gal - The Planted Tank Forum
 
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post #1 of 11 (permalink) Old 02-17-2012, 02:32 AM Thread Starter
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DIY LED Build for 20 Gal

Well I'm about to bite the bullet and start my own DIY LED fixture. The thing is I'm completely lost when it comes to picking out how many LEDs, what dimmer etc etc set up for my tank.

I have a standard 20 gal tank(24x12x18 I believe). I am thinking about growing a UG carpet or maybe HC and some mosses.

I was thinking of getting the following:
1. 2 strips of
1.1" x 18" Aluminum Heatsink
2. 14 CREE XP-G R5 Cool White 3W LED
3. 14 60 Degree CREE XP-G Lens/Optics

after this, I'm lost lol

I don't know if this is too little or too much light for my tank. I don't know what kind of dimmer/driver i should get.


Can you guys help!? Thanks in advance!
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post #2 of 11 (permalink) Old 02-17-2012, 03:49 AM
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A standard 20 gallon tank is about 24L x 12D x 16H. A LED light as you described should give you about 350 micromols of PAR at 700 mAmps, or 190 at 350 mAmps. That is way more light than you need. Hang it 16 inches above the top of the tank and you would get about half of those numbers, which is still a bit high. Use only 12 LEDs, and that drops to about 170 and 90 micromols with it sitting on the tank, or about 90 and 50 with it hanging 16 inches above the top of the tank. The latter numbers are about what you should shoot for.

Hoppy
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post #3 of 11 (permalink) Old 02-17-2012, 04:10 AM Thread Starter
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how do you find out these numbers? and what what are micro mols of PAR and mAmps? Sorry for asking for a crash course. lol
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post #4 of 11 (permalink) Old 02-17-2012, 07:58 PM
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I agree with hoppy. Your phasers are set on "fryalate."

I use 29 Crees to light my 36x18x22 high 57 gal (see the signature), and I can easily get it to pearl on full blast. The fixture is about 8" from water surface. I run it well below full intensity most of the time.

If cost is an issue, I'd do a single string of 14 LEDs on a 20g--maybe 3 Royal blues, 7 cool whites, and 4 warm whites. If cost were no object, I'd go with two strings of 8 each. One with 4 Royal Blues and 4 Cool whites. The other with 4 cool whites and 4 warm whites. Put them both on Meanwell 48D variable drivers, and fiddle to get the color balance you want.

sns26

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post #5 of 11 (permalink) Old 02-17-2012, 11:09 PM
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Look into Cree XM-Ls i've been thinking about using those, can get them imported from hong kong for around $9-10 each. comparable to XP-Gs at 3 amps, 20% more efficient at 1.3 amps.
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post #6 of 11 (permalink) Old 02-17-2012, 11:45 PM
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Quote:
Originally Posted by ilurk View Post
Look into Cree XM-Ls i've been thinking about using those, can get them imported from hong kong for around $9-10 each. comparable to XP-Gs at 3 amps, 20% more efficient at 1.3 amps.
Seriously- 12 XP-G's will provide more light than you'll ever need on a 20 gallon tank. Don't get me wrong- The XM-L's are great leds,but for your application they would be "beyond overkill". Save some money upfront by purchasing the cheaper XP-G's and roll the money into a dimming controller or some other neat gadget for the tank.
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post #7 of 11 (permalink) Old 02-18-2012, 01:22 AM
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ledgroupbuy has XML's for like $7 each, two of those over a 20 would be enough. The real problem with XML series is finding a power supply that will drive them at higher currents, that isn't fantastically expensive. "powergate llc" (google them or try the obvious) has the whole line of meanwell drivers at very good prices, and you can get a suitable unit there for sure. With fewer LEDs you also buy fewer optics and need make fewer connections, can save you a good bit of time.

I have some Citizen 18w 5000k 85 CRI emitters that I am really liking over my planted tank with a peacock cichlid in it. He glows orange under this one, and I really like the single light source, the ripple isn't so overwhelming. I had(still have actually) an array of 8 XPG 5500k (WH bin code) over the tank, it had a greenish tinge reminiscent of cheap cool white fluoros. The citizen emitters cost me $9.53 each, not at all bad for what they are, and you can drive them at 30w (datasheet max for this model). They're around 75 lumens/watt, which is not great until you compare to other high CRI emitters.
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post #8 of 11 (permalink) Old 02-18-2012, 04:13 AM
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Quote:
Originally Posted by dirrtybirdy View Post
how do you find out these numbers? and what what are micro mols of PAR and mAmps? Sorry for asking for a crash course. lol
If you plan to build a LED light you should first learn what mAmps (miliamps) are, and what PAR (photosynthetically active radiation) is.

I used data from the LED lights I have made to develop an equation that relates how much light you get in PAR units (micromols of photons per square meter per second) to number of LEDs, how far apart they are spaced, what their lumen output is vs LED current, what the lens cone angle for them is, how far from the light you want to know the PAR is, etc. That equation, combined with data from Cree for the LEDs gave me those numbers.

Hoppy
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post #9 of 11 (permalink) Old 02-18-2012, 03:39 PM Thread Starter
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Quote:
Originally Posted by Hoppy View Post
If you plan to build a LED light you should first learn what mAmps (miliamps) are, and what PAR (photosynthetically active radiation) is.

I used data from the LED lights I have made to develop an equation that relates how much light you get in PAR units (micromols of photons per square meter per second) to number of LEDs, how far apart they are spaced, what their lumen output is vs LED current, what the lens cone angle for them is, how far from the light you want to know the PAR is, etc. That equation, combined with data from Cree for the LEDs gave me those numbers.

This is what I'm trying to figure out. I want to build something that is relevant to what my tank needs. Im so lost when PAR and mAmps gets involved. Then when you start throwing in the height that it hangs from the tank, dimmers, drivers etc...im just completely lost

Quote:
Originally Posted by tentacles View Post
ledgroupbuy has XML's for like $7 each, two of those over a 20 would be enough. The real problem with XML series is finding a power supply that will drive them at higher currents, that isn't fantastically expensive. "powergate llc" (google them or try the obvious) has the whole line of meanwell drivers at very good prices, and you can get a suitable unit there for sure. With fewer LEDs you also buy fewer optics and need make fewer connections, can save you a good bit of time.

I have some Citizen 18w 5000k 85 CRI emitters that I am really liking over my planted tank with a peacock cichlid in it. He glows orange under this one, and I really like the single light source, the ripple isn't so overwhelming. I had(still have actually) an array of 8 XPG 5500k (WH bin code) over the tank, it had a greenish tinge reminiscent of cheap cool white fluoros. The citizen emitters cost me $9.53 each, not at all bad for what they are, and you can drive them at 30w (datasheet max for this model). They're around 75 lumens/watt, which is not great until you compare to other high CRI emitters.
Idk like to spend no more than $150. This is going to be my first LED build and I just want to make sure I know what I'm doing before throwing in more money. So you think two XML emitters are enough for a 20gal? That seems like its too little? I wouldn't know though lol



Quote:
Originally Posted by O2surplus View Post
Seriously- 12 XP-G's will provide more light than you'll ever need on a 20 gallon tank. Don't get me wrong- The XM-L's are great leds,but for your application they would be "beyond overkill". Save some money upfront by purchasing the cheaper XP-G's and roll the money into a dimming controller or some other neat gadget for the tank.
how many XP-G's would I need and what kind of driver?

Quote:
Originally Posted by ilurk View Post
Look into Cree XM-Ls i've been thinking about using those, can get them imported from hong kong for around $9-10 each. comparable to XP-Gs at 3 amps, 20% more efficient at 1.3 amps.
Quote:
Originally Posted by sns26 View Post
I agree with hoppy. Your phasers are set on "fryalate."

I use 29 Crees to light my 36x18x22 high 57 gal (see the signature), and I can easily get it to pearl on full blast. The fixture is about 8" from water surface. I run it well below full intensity most of the time.

If cost is an issue, I'd do a single string of 14 LEDs on a 20g--maybe 3 Royal blues, 7 cool whites, and 4 warm whites. If cost were no object, I'd go with two strings of 8 each. One with 4 Royal Blues and 4 Cool whites. The other with 4 cool whites and 4 warm whites. Put them both on Meanwell 48D variable drivers, and fiddle to get the color balance you want.
14 emitters sounds more reasonable to me. If i do a strip of 14, I would have to space them out at 1.5 inches, correct? would that be sufficient for heat dissipation?


I know there are a lot of thread on DIY led builds and I have been researching them for weeks now and I alway end up more confused. I guess my real question is how do I calculate PAR, mAmps, what dimmer, what driver, and what optic lens?

Sorry for the redundancy. Just trying to learn as much as I can. Thanks again for all your input and replies!
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post #10 of 11 (permalink) Old 02-18-2012, 06:26 PM
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Originally Posted by dirrtybirdy View Post
I guess my real question is how do I calculate PAR, mAmps, what dimmer, what driver, and what optic lens?
https://www.plantedtank.net/forums/di...ml#post1443426 is the equation I worked out that fits the data I have, and has some theoretical basis. It seems to work reasonably well for LED lights that are in one or two rows across the top of the tank. But, it isn't accurate enough to hit an exact PAR reading. So, it works best if you use the maximum LED current you might want to run to figure out what configuration of LEDs to use, then use dimmable drivers so you can adjust downward to some reasonable measured PAR. That means borrowing a PAR meter to make that adjustment.

Hoppy
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post #11 of 11 (permalink) Old 02-23-2012, 04:09 AM Thread Starter
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ok guys,

i think im going to go with chinese leds. I have narrowed it down to this set up

Quantity: 10
Power: 3W
Emitted Color: White
Color Temperature: 6500K~7500K
DC Forward Voltage (VF): 3.2V~3.8V
DC Forward Current (IF): 700mA
Maximum Pulse Voltage: 2.9V
Maximum Pulse Current: 750mA
Brightness Lumens: 150LM~180LM
LED Diameter: 20mm
Viewing Angle: 120 Degree

Quantity: 5pcs
Power: 3W
Emitted Color: Cool White/Cold White
Color Temperature: 10000K(15000K or 20000K for your choice)
DC Forward Voltage (VF): 3.2V~3.8V
DC Forward Current (IF): 700mA
Maximum Pulse Voltage: 3.9V
Maximum Pulse Current: 750mA
Brightness Lumens: 150LM~180LM
LED Diameter: 20mm
Viewing Angle: 120 Degree

Quantity: 2pc
Working temperature: -20-80 Deg
Protection Rank: IP67 waterproof
Input Voltage: AC85V ~ 265V 50/60HZ
Output Voltage: 20V~36V
Output Current: 620mA
Size: (L) 92mm*(W)28mm*(H)22mm
Usage: Used for the 7~10pcs 3W LED Light


Parameters for Heatsink:
Quantity: 15pcs
Heatsink Size: L3.5xW3.5xH1cm
Material: Aluminum
Net weight: 18 g
Gross weight: 25 g
Color: Black

Parameters for LED Dimmer:
Quantity: 2pc
Working temperature: -20-60℃
Touchable: Yes
Voltage: 12V (DC24V for your choice)
Output: 1 channel
Output current: <8A
Power output: 96 W
External dimension: L89 * W59 * H35 mm
Packing size: L96 * W64 * H65 mm
Net weight: 55 g
Gross weight: 80 g
Static power consumption: <1 W

what do you guys think? i dont ant to spend too much money on my first diy kit. I would rather learn with a tester diy first. please let me know what you guys think...THANKS!
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