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Unread 07/06/2013, 07:06 PM   #1
reefgoddess808
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LED conversion

What is the conversion for LED lights compared to CF or T5 type bulbs wattage? I know for a reef you should have 2 watts or more per gallon. So how do you know if you have enough LED light?

Thank you in advance~


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Unread 07/06/2013, 07:21 PM   #2
crsswift70
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The old watts per gallon doesn't apply to LED's. I would read up on what other people are using on your size tank as well as what is commercially produced to get an idea. For example, my GU10 LED DIY hood has 32 3w bulbs and it grows LPS and softies fine. My new DIY hood will have 48 3w LED's mounted on stars with 80deg lenses. However, i am using more bulbs for color as opposed to just blue and white.


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Unread 07/06/2013, 07:27 PM   #3
bnumair
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LED dont fall under that rule. u need PAR readings for led.
200 PAR across sand bed will let u keep a mixed reef with no problem.


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Unread 07/06/2013, 07:46 PM   #4
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Awesome! Thank you for the info. Im wanting to start a 5.5 gal nano, with hopes of acros so I was trying to figure out the most light for a little tank.


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Unread 07/06/2013, 07:57 PM   #5
bnumair
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sps acro PAR requirements are 400+


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Unread 07/07/2013, 12:53 PM   #6
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Are lumens and PAR the same thing? I saw an LED strip that would fit and it said 400 lumens, 17000k daylight. No wattage or PAR mentioned.


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Unread 07/07/2013, 01:00 PM   #7
bnumair
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no lumens and par is not the same.


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Unread 07/07/2013, 07:28 PM   #8
reefgoddess808
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So how do you figure out the PAR of a particular fixture? Is there a per LED PAR #?


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Unread 07/07/2013, 07:59 PM   #9
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u will need a PAR meter to determine PAR of a fixture, any light source MH, T5 leds ...


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Unread 07/07/2013, 09:15 PM   #10
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PAR meters under report the light from LEDs. I don't understand the reasons personally, but it's well documented. Its easy to look it up.

But I have read that a good rule of thumb is for LEDs running whites to royal blues in a 1:2 ratio, that the "true" PAR is between 25% and 33% more than what the reader reports. I used that rule of thumb when I converted MH/PC to LED a few years ago, and it worked out very well for me.

Something to consider if you can put your hands on a PAR meter.


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Unread 07/08/2013, 04:18 AM   #11
Ron Reefman
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Quote:
Originally Posted by scolley View Post
PAR meters under report the light from LEDs. I don't understand the reasons personally, but it's well documented. Its easy to look it up.

But I have read that a good rule of thumb is for LEDs running whites to royal blues in a 1:2 ratio, that the "true" PAR is between 25% and 33% more than what the reader reports. I used that rule of thumb when I converted MH/PC to LED a few years ago, and it worked out very well for me.
Something to consider if you can put your hands on a PAR meter.
scolley, I don't mean to be picky here, but first you say it's well documented and easy to look up and then you give out poor info? The 'true PAR' of leds is not even close to 25%-30% off what a PAR meter says. Here is info from Apogee (the brand most of us use):

"*Spectral errors were typically smaller for common electric lights relative to LEDs, where spectral errors for all quantum sensors were less than 4% for common electric lights and less than 11% for LEDs.
*Spectral errors were typically smaller for mixed and broadband (white) LEDs relative to single color LEDs, where spectral errors for all quantum sensors were less than 4 % for mixed LEDs.
*Quantum sensors can be a very practical means of measuring PPF from LEDs, but spectral errors must be considered.
Errors presented in the table above can be used as correction factors for different electric light sources."


Here is a link to the site and the entire report:
http://www.apogeeinstruments.com/con...ember-2012.pdf

Here is a chart of error rates and the worst value is less than 11%. Your 25-30% figure is way too high.

All Quantum/PAR sensors on the market experience a certain level of errors under different electric light sources. The following data can be used to adjust the PAR readings of Apogee Quantum sensors to achieve highly accurate readings. Please note that these errors apply only to quantum sensors that are pre-calibrated for electric lights, and for the Quantum Meter when it is set to "electric light" mode.

LED Type
Error [%] for Apogee Quantum Sensor
Cool White -4.2
Neutral White -6.1
Warm White -9.9
Blue (448 nm) -10.7
Green (524 nm) 5.8
Red (635 nm) 4.7
Red, Blue 2.7
Red, Green, Blue 3.5

Here is a link to the whole report:
http://www.apogeeinstruments.com/aquarium-par-meters/


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Last edited by Ron Reefman; 07/08/2013 at 04:24 AM.
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Unread 07/08/2013, 04:36 AM   #12
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Quote:
Originally Posted by reefgoddess808 View Post
So how do you figure out the PAR of a particular fixture? Is there a per LED PAR #?
PAR values varies with the distance from the led and the clarity of the medium the light is passing through (air or water). Near an led could be as high as 2000 and at 24" away through clear water could be 200. If you get a good, full spectrum fixture (5-10 colors of leds including 2-3 blues and 2-3 whites) with dimmers to control the output you should be OK. I haven't dealt with any led fixtures that small or I'd offer a suggestion.

Also, leds often have lenses that make all the light shine almost directly down, so they are more 'intense' and can 'burn' corals that haven't been acclimated to them, so be careful. Also, since there isn't as much 'reflective' light, leds tend to have more contrast to them. By that I mean things are either in full light, or in deep shadows, there isn't a lot of light bouncing around creating any semi shady areas of medium light. It's just bright or it's dark when compared to t5 or mh fixtures. Some people really don't like that look and others love it, it's all a matter of personal taste.

Good luck.


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Unread 07/08/2013, 05:26 AM   #13
reefgoddess808
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Thank you so much! All this is for a tiny little 5.5 gal that I want to make a mini reef! Its incredibly difficult to find (afordable) lighting period for a tank that size. Its only 12" deep and 16" wide. I saw a marineland LED set up for about $40. I think that may be the route I go. I would really like to have at least one acro of some sort in a mixed reef. Does that seem possible in a tank that size? I currently have a 56 gal FOWLR set up so I have no experience as of yet with corals. I really appreciate everyones input! Thank you all again so much!


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Unread 07/08/2013, 07:37 AM   #14
scolley
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Quote:
Originally Posted by Ron Reefman View Post
scolley, I don't mean to be picky here, but first you say it's well documented and easy to look up and then you give out poor info? The 'true PAR' of leds is not even close to 25%-30% off what a PAR meter says. Here is info from Apogee (the brand most of us use)...
Sorry for going OT for a moment, but I'm kind passionate about the following reply...

WOW! Ron you were not picky AT ALL! Based on solid, available information, the rule of thumb that I posted was WAY off base. Thank you for posting that! It's awesome data, that I had not seen. I'll be doing conversion calculations ASAP on my measured PAR in my tank based on this info.

As it happens, I was quoting old information from way, way back in the very first days of LED use. Clearly better information has come available, and you were ABSOLUTLY right to call me on it. Thank you Ron. If we had more such activity going on at RC, this hobby would be a LOT easier. Thank you. Please see my sig if that point is not clear.


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Unread 07/08/2013, 02:32 PM   #15
Ron Reefman
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reefgodess, you might look at Build My LEDs based in Texas. They will make various length leds for you. I met the owners at MACNA last year in Dallas and they are good people.

scolley, thanks for being cool about my making my point. If people would be a bit more open minded and civil here on RC a lot better info would get disseminated. My wife is the Head Librarian at our branch of the county library and she is always asking for more citations when people start spouting off 'facts'. I try to be clear about things I can prove and things that are just my opinion. And your sig is right on and your avatar cracks me up.

BTW, just to rub it in when I get the chance, we are sitting by the pool and bar at our hotel in Key West getting ready to go to the Dry Tortugas tomorrow for an all day snorkel! Photos to be posted in the lounge forum Tues or Wed night! My Belize and Middle Keys photos are already there. Three nice snorkel vacations in 3 months... and it's more my wife's idea than it is mine! I am one lucky puppy.


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Unread 07/08/2013, 06:49 PM   #16
scolley
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Apologies to the OP, just a bit more OT from me, and I'll be quiet...
Quote:
Originally Posted by Ron Reefman View Post
And your sig is right on and your avatar cracks me up.
Thanks for the feedback on that. I've used that for years in every forum I participate in. Why? Look at him...
He's cool. Must be - look at those shades.
He's important. Must be - check out the suit.
He's got something to say. Cleary - his mouth it open.
Only thing is... LOL, he just doesn't seem to realize he's a chimp.
Some how it has always seemed appropriate. If the shoe fits...

Have fun diving! And thanks for rubbing it in!

OK. I'm done with OT now. Thanks.


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Unread 07/08/2013, 08:18 PM   #17
reefgoddess808
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Talk away! LOL Thanks Ron for the info I will be checking it out!


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