PAR 20, 30, 38 LED bulbs (3 watt cree)
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Old 09-03-2014, 08:11 PM   #1
Joost
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PAR 20, 30, 38 LED bulbs (3 watt cree)


Hello fellow planted tank fanatics,


For my 60 cm * 30 cm * 30 cm (length, depth, height), 54 litre aquarium I'm looking for new aquarium light bulbs. After browsing on the internet for a while I came across the following light, also known as PAR 38 led bulbs. After spending some time doing research on these lights, I found out that there's not much information to be found regarding planted tanks, which is why I made this post. However, a lot of people seem to use this in the reef section of the aquarium hobby.

The PAR 38 light bulb I'm talking about is illustrated below.



For more information about these lights (chip power, actual power, colour temperature, beam angle etc.) click on the link below.
http://www.aliexpress.com/item/FREE-...812470561.html

I'm interested in these light bulbs because it seems to be a different and fairly cheap alternative to the CFL bulbs I used to have above my planted tank. To hang these lights I'm planning to use two IKEA tertial desk lamps currently own.



I'd like to use two of these lamps above my aquarium to create an even spread, but I have no clue which wattage to pick, which beam angle would be the best option, if the PAR (or PUR?) of these lights is sufficient and if the light has the right spectrum.

I'm aiming for "high light" My aquarium has the following specifications:

- substrate: dirt capped with fine gravel;
- EI dosing;
- Pressurized co2;
- 60 cm * 30 cm * 30 cm (length, depth, height).

All I've found so far are 6500k and reef PAR 38's. I haven't found any PAR 38's made for planted tanks with for example white and red lights.


I'm hoping you guys could inform me about the PAR 38 led bulbs, especially people that have experience with this light. I'm looking for the following information:

- sufficient as high light? (PAR, PUR)
- even spread? which beam angle would be the most suitable if 2 bulbs are used when the length of the aquarium is 60 cm, depth 30 cm and width 30 cm?)
- which wattage would be the best choice?
- does the light emit the right colour spectrum wise?


Any help regarding these lights would be greatly appreciated.

Best regards,

Joost

Last edited by Joost; 09-03-2014 at 08:35 PM.. Reason: Added info.
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Old 09-04-2014, 01:41 AM   #2
jeffkrol
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The cheap ones have a high failure rate.......
and the FW "tailored" ones are expensive
http://www.ecoxotic.com/par38-led-aq...th-remote.html

Beam angle and spread will depend on height from top of tank.

White LED's (all) are inherently high in PAR... w/ warmer temps being a tad better.. (arguable)

That said 2=14W over your tank @ 90degrees 6" above the water line should be sufficient to spread 12".
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Old 09-04-2014, 07:12 AM   #3
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Hi Joost, ook goede middag,

Some of the Chinese Cool Whites are deficient in the violet (≈400nm) range of the spectrum because the Chinese seem to use a 475nm source to excite the green, yellow and red phosphors.
By comparison, CREE use a 450nm source. This means that CREE has a better cover of the 400nm range.
In my tank, nothing would grow under Chinese Cool Whites untill I supplemented the spectrum with some 420nm UV LEDs.
Now everything is fine.

No manufacturer ever publishes PAR information, but most Cool Whites emit about 1.0 to 1.6 PAR per Watt (higher values at the lower bias currents).
These values are obtained from relevant spectra.

Work out the total PAR and divide the result by the total water surface area to get an average PAR/mē (PPFD) applicable to the top surface of your tank (assuming an even light distribution across the surface).

I'll leave it at this, until you have more questions that I can answer.
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Old 09-04-2014, 03:12 PM   #4
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Thank you for your answers so far, they've been helpful in a way. Unforntunately it still is hard to make a decision based on the responses so far. I'd be great if people who actually own, or owned these lights could give some kind of response, perhaps accompanied with a recommendation like jeffkrol.


Quote:
Originally Posted by Greystoke View Post
Hi Joost, ook goede middag,

Some of the Chinese Cool Whites are deficient in the violet (≈400nm) range of the spectrum because the Chinese seem to use a 475nm source to excite the green, yellow and red phosphors.
By comparison, CREE use a 450nm source. This means that CREE has a better cover of the 400nm range.
Apparently these lights have CREE leds installed, so that that won't be an issue I presume.
http://www.aliexpress.com/item/FREE-SHIPPING-Ultra-Bright-CREE-E27-Dimmable-9W-10W-14W-30W-PAR20-PAR30-PAR38-LED-Light/1812470561.html?PID=6147090&src=ale&URL=http%3A%2F %2Fwww.aliexpress.com%2Fitem%2FFREE-SHIPPING-Ultra-Bright-CREE-E27-Dimmable-9W-10W-14W-30W-PAR20-PAR30-PAR38-LED-Light%2F1812470561.html&cv=11032041&cn=null&tp1=1b ma8umekmvj0&tracelog=null&af=cj_6147090&vd=30
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Old 09-04-2014, 03:43 PM   #5
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Well until there are more current users commenting..
Eye candy (see paludarium link and some food for thought):
http://www.plantedtank.net/forums/sh...ighlight=par30

http://www.plantedtank.net/forums/sh...01#post5226001
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Old 09-04-2014, 04:30 PM   #6
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A Hi light tank requires at least 200 to 250 PPFD at the water surface.
Assuming that you don't lose any light in the process, you will need 40 to 45 PAR source lights, which boils down to 30 to 40 Watt of Cool white LED light installed.
This agrees roughly with Jeff's recommendation.
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Old 09-04-2014, 06:55 PM   #7
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Just found the following Par 30 led :
http://www.aliexpress.com/item/2014-...888661090.html

It says the output of the led is 7 x 3 Watt. My question is however, do the LEDs really run at 3 Watt or is this some kind of scam? I'm wondering this because the heatsink seems to be rather small and the pricing is really low.
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Old 09-05-2014, 02:26 AM   #8
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LEDs are Light emitting diodes biased in forward current. The forward voltage across the diode is around 3-4V:

Rated data for the CREE xml Cool White:
Vfw, Ibias, Watt, Lumen, PAR
2.75 V, 350 mA, 0.96 W, 145 Lm, 1.73 PAR
2.92 V, 700 mA. 2.05 W, 280 Lm, 3.35 PAR
3.01 V, 1000 mA, 3.01 W, 393 Lm, 4.71 PAR
3.12 V, 1500 mA, 4.68 W, 568 Lm, 6.80 PAR
3.30 V, 3000 mA, 9.89 W, 1009 Lm, 12.0 PAR
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Old 09-05-2014, 03:43 AM   #9
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Quote:
Originally Posted by Joost View Post
Just found the following Par 30 led :
http://www.aliexpress.com/item/2014-...888661090.html

It says the output of the led is 7 x 3 Watt. My question is however, do the LEDs really run at 3 Watt or is this some kind of scam? I'm wondering this because the heatsink seems to be rather small and the pricing is really low.
Best to think of them as 3W "class"...
Wattage will depend on drive voltage/current.. which is also variable by internal factors (heat, driver ect.)





http://www.amperor.com/products/led/...ed_driver.html

Last edited by jeffkrol; 09-05-2014 at 03:59 AM.. Reason: data
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