How many Watts of LED?

RossC · 10-08-2012, 11:56 PM

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

**Hoppy** · 10-09-2012, 01:35 AM

This might help answer your question: http://www.plantedtank.net/forums/sh...d.php?t=168999

RossC · 10-09-2012, 10:25 AM

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 · 10-09-2012, 10:56 AM

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

**Hoppy** · 10-09-2012, 03:23 PM

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)

MegganKelley · 10-10-2012, 09:38 AM

I'm struggling to work out the equation, if anyone could help me please?

**Hoppy** · 10-10-2012, 03:42 PM

Quote:

Originally Posted by MegganKelley

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.

10-08-2012, 11:56 PM	#1
RossC Newbie (View User Tanks) PTrader: (0/0%) 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 __________________

10-09-2012, 01:35 AM	#2
Hoppy Planted Tank Guru (View User Tanks) PTrader: (54/100%) Join Date: Dec 2005 Location: Sacramento, CA Posts: 17,218	This might help answer your question: http://www.plantedtank.net/forums/sh...d.php?t=168999 __________________ Hoppy

10-09-2012, 10:25 AM	#3
RossC Newbie (View User Tanks) PTrader: (0/0%) 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 __________________

10-09-2012, 10:56 AM	#4
RossC Newbie (View User Tanks) PTrader: (0/0%) 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 __________________

10-09-2012, 03:23 PM	#5
Hoppy Planted Tank Guru (View User Tanks) PTrader: (54/100%) Join Date: Dec 2005 Location: Sacramento, CA Posts: 17,218	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

10-10-2012, 09:38 AM	#6
MegganKelley Newbie (View User Tanks) PTrader: (0/0%) Join Date: Oct 2012 Location: fgfhgh Posts: 3	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!

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