How many Watts of LED? - The Planted Tank Forum
Old 10-08-2012, 11:56 PM Thread Starter
Newbie

Join Date: Oct 2012
Location: Walsall, UK
Posts: 3
How many Watts of LED?

Hey everyone, I'm planning on converting my 95 litre, heavily planted, high tech tank currently using a 20W T8 to a custom DIY LED setup. Realistically I don't want to exceed 45W, I've been looking at using Cree XP-G 3W's as I've heard good things about them. Roughly speaking how many would you recommend for a medium light output?

Tank Specs:
95 litre / 25 US Gal
L80cm x H45cm x D30cm
Pressurized CO2 Injected
TNC Lite Liquid Ferts Weekly
40-50% WC Weekly
1000LPH Cannister Filter

Thanks

RossC is offline

Old 10-09-2012, 01:35 AM
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Location: Sacramento, CA
Posts: 21,015
This might help answer your question: One Way to Design a Planted Tank LED Light

Hoppy
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Old 10-09-2012, 10:25 AM Thread Starter
Newbie

Join Date: Oct 2012
Location: Walsall, UK
Posts: 3
I'm struggling to work out the equation, if anyone could help me please?
LED model Cree XP-G R5
LED current 3
lumen output per LED 118.8 (L)
Height of light from substrate 24 inches (H)
Optic cone angle 60 (probably 60 or 40 degrees) (ø)

Thank you

RossC is offline

Old 10-09-2012, 10:56 AM Thread Starter
Newbie

Join Date: Oct 2012
Location: Walsall, UK
Posts: 3
I found the working PAR calculator and if i've done it correctly in order to get PAR 50 at 24inches I need to space them 1.38inches apart in a single row. Does this sound about right?
So if my bar is 80cm long (32inches) I need about 24 LED's

RossC is offline
Old 10-09-2012, 03:23 PM
Planted Tank Guru

Join Date: Dec 2005
Location: Sacramento, CA
Posts: 21,015
I would use one row of LEDs, given that the tank's front to back dimension is only about 12 inches. The lumen output per LED is about 400 lumens, not 120, and this is at 1.5 amps of current. That gives a spacing of 2.5 inches, or about 12-13 LEDs (60 degree optics)

Hoppy
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Old 10-10-2012, 09:38 AM
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I'm struggling to work out the equation, if anyone could help me please?

Creating so touching plots and decent character developement, Mickey's Twice Upon A Christmas DVD will be the next huge thing on your TV with Rules of Engagement Seasons 1-4 DVD!
MegganKelley is offline
Old 10-10-2012, 03:42 PM
Planted Tank Guru

Join Date: Dec 2005
Location: Sacramento, CA
Posts: 21,015
Quote:
Originally Posted by MegganKelley View Post
I'm struggling to work out the equation, if anyone could help me please?
There are 3 versions of a calculator - spreadsheet - that you can use without even knowing what the equation is. I always use those calculators now.

Hoppy
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 Tags cree, diy, led, planted

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