Lighting intensity questions

AnnaCassandra · 08/13/2018, 11:47 AM

I was watching the BRS 160 update, they have LED lights spaced 1 ft apart operating at 40-50% max daily (plus t5s)- it seems fairly common for people to buy multiple extremely expensive LED fixtures and operating them at less than half their full intensity, what is the advantage of this vs having fewer lights spaced further apart and maybe a further distance from the tank operating at a higher intensity? If you truly need to have a lower intensity light spaced closer together why aren't manufacturers capturing this and producing cheaper lower wattage lights?

lpsouth1978 · 08/13/2018, 01:26 PM

I am no expert, but I believe the idea is to get the most even spread and reduce the shadowing effect of LED's. The more fixtures you put over the tank the more evenly the light will be distributed around the tank. More LED's also reduces the "self shadowing" that can be a problem.

That being said, BRS is not concerned with the cost of the setup as most of us are. They are able to put whatever lights they want over a system and not really feel the financial strain that you or I might.

dave540 · 08/13/2018, 06:10 PM

LED fixtures are point source lighting to the extreme. Corals (sps in particular) can start to shade themselves as they grow. Sometimes this causes corals to grow in weird ways and sometimes the shaded areas die. Adding more fixtures helps reduce the shading in the tank and as a result corals can grow and develop more easily into large healthy colonies.

Or instead of buying more expensive LED fixtures you can just add some t5s into the mix and save thousands of dollars in equipment cost. Give your tank the correct par and spectrum without the need to tinker with a controller.

Sent from my iPhone using Tapatalk

Uncle99 · 08/13/2018, 08:37 PM

Some LEDs are quite powerful and focused, I can't run mine more than 50%, just too bright.
To much space creates a big drop in PAR.

mcgyvr · 08/14/2018, 08:19 AM

A light run at anything less than full strength just means the light has too much power for the depth of the tank or the needs of the corals in it..
A deeper tank requires more light power to penetrate further down...
If you had a deeper tank you would need more power.. (or higher light demanding corals,etc...)...

More power does not equal greater spread at the same depth.. It just equals higher intensity..

Plain and simple..

LPS_Blasto · 08/15/2018, 05:20 AM

I use a simple formula to calculate LED wattage.

Old school rule of thumb (for me... your thumbs may be different... and may smell)
4--5 watts per gallon when using T5HO or Metal Halide. Thats good for most corals EXCEPT SPS. Anything else will do fine under that much light, and some may need to be placed lower in the tank. Typically works fine for tanks around 16--24 inches in depth.

To convert to LED, simply divide by 3.7

100g tank with T5HO = 400--500 watts
100g tank with LED = 100--135 watts

Your mileage may vary.

lpsouth1978 · 08/15/2018, 01:43 PM

Quote:

Originally Posted by LPS_Blasto

I use a simple formula to calculate LED wattage.

Old school rule of thumb (for me... your thumbs may be different... and may smell)
4--5 watts per gallon when using T5HO or Metal Halide. Thats good for most corals EXCEPT SPS. Anything else will do fine under that much light, and some may need to be placed lower in the tank. Typically works fine for tanks around 16--24 inches in depth.

To convert to LED, simply divide by 3.7

100g tank with T5HO = 400--500 watts
100g tank with LED = 100--135 watts

Your mileage may vary.

Not to rain on your parade, but this seems VERY flawed to me. IME there really is no "rule of thumb" for LED's. There are just WAAAAYYYY to many variables (ie- different LED's, lenses, drivers, coral requirements, etc.).

For example - I had a 165W Chinese black box over my 40b and it simply was not enough, partly due to the lenses used, partly due to the spread, and partly due to the inferior LED's used. I ran these @ 100% Blue and 50% white. In contrast, When I switched over to AI Prime HD's (x2) I only run them at about 30W/each for a total of 60W.

So, with the CBB I was using ~120W, but with the Primes only ~60w. By your "rule of thumb", the CBB would be enough light for a ~150 gallon tank and the Primes for ~180. This simply is not the case. IME we CANNOT use watts-per-gallon to determine the lighting needs of our tanks when using LED's.

I hope this makes sense.

LPS_Blasto · 08/15/2018, 08:04 PM

Quote:

Originally Posted by lpsouth1978

Not to rain on your parade, but this seems VERY flawed to me. IME there really is no "rule of thumb" for LED's. There are just WAAAAYYYY to many variables (ie- different LED's, lenses, drivers, coral requirements, etc.).

For example - I had a 165W Chinese black box over my 40b and it simply was not enough, partly due to the lenses used, partly due to the spread, and partly due to the inferior LED's used. I ran these @ 100% Blue and 50% white. In contrast, When I switched over to AI Prime HD's (x2) I only run them at about 30W/each for a total of 60W.

So, with the CBB I was using ~120W, but with the Primes only ~60w. By your "rule of thumb", the CBB would be enough light for a ~150 gallon tank and the Primes for ~180. This simply is not the case. IME we CANNOT use watts-per-gallon to determine the lighting needs of our tanks when using LED's.

I hope this makes sense.

Eh, your mileage may vary. Your thumbs must be different than mine.

Never said it was gospel and I thought it was pertinent to the OP's discussion. I'm not here to debate or argue with anyone. Best of luck to ya.

Uncle99 · 08/15/2018, 08:25 PM

It's kinda like the 1 fish per 5g rule which could equal 10 tangs in a 50.

LPS_Blasto · 08/16/2018, 07:40 AM

Quote:

Originally Posted by Uncle99

It's kinda like the 1 fish per 5g rule which could equal 10 tangs in a 50.

I always heard 1 inch of fish per 5 gallons.

Different thumbs. Different rules.

mcgyvr · 08/16/2018, 07:48 AM

Quote:

Originally Posted by LPS_Blasto

Different thumbs. Different rules.

Damn you man for attempting baseline simplification in this hobby.. We want to keep it convoluted around here..

And damn you for initially including the statement to the fact that you were generalizing.. No fair.. How can we even argue with that.. Or wait.. what?

LPS_Blasto · 08/16/2018, 09:30 AM

Quote:

Originally Posted by mcgyvr

Damn you man for attempting baseline simplification in this hobby.. We want to keep it convoluted around here..

And damn you for initially including the statement to the fact that you were generalizing.. No fair.. How can we even argue with that.. Or wait.. what?

It's the internet. Ya practically gotta be a lawyer to post anything without being flamed and dragged through the mud for having a different opinion than somebody else.

lpsouth1978 · 08/16/2018, 10:12 AM

WOW....

I apologize if my statements came off as argumentative, or like I was flaming anyone. That was certainly not my intent. I was simply trying to educate as to why the watts-per-gallon rule is not ideal. If it works for you, I have no problem with that, but it does not work in most cases (when talking LED's).

Misled · 08/16/2018, 11:32 AM

They like to argue!!!

LPS_Blasto · 08/17/2018, 09:36 AM

Quote:

Originally Posted by Misled

They like to argue!!!

You know what they say about arguing with people on the internet......

08/13/2018, 11:47 AM	#1
AnnaCassandra Registered Member Join Date: Dec 2015 Location: Edmonton, Alberta Posts: 100	Lighting intensity questions I was watching the BRS 160 update, they have LED lights spaced 1 ft apart operating at 40-50% max daily (plus t5s)- it seems fairly common for people to buy multiple extremely expensive LED fixtures and operating them at less than half their full intensity, what is the advantage of this vs having fewer lights spaced further apart and maybe a further distance from the tank operating at a higher intensity? If you truly need to have a lower intensity light spaced closer together why aren't manufacturers capturing this and producing cheaper lower wattage lights?

08/13/2018, 01:26 PM	#2
lpsouth1978 Registered Member Join Date: Jan 2007 Location: Arizona Posts: 915	I am no expert, but I believe the idea is to get the most even spread and reduce the shadowing effect of LED's. The more fixtures you put over the tank the more evenly the light will be distributed around the tank. More LED's also reduces the "self shadowing" that can be a problem. That being said, BRS is not concerned with the cost of the setup as most of us are. They are able to put whatever lights they want over a system and not really feel the financial strain that you or I might. __________________ Current tank: 40B work in progress w/20L sump

08/14/2018, 08:19 AM	#5
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	A light run at anything less than full strength just means the light has too much power for the depth of the tank or the needs of the corals in it.. A deeper tank requires more light power to penetrate further down... If you had a deeper tank you would need more power.. (or higher light demanding corals,etc...)... More power does not equal greater spread at the same depth.. It just equals higher intensity.. Plain and simple.. __________________ Who me?

08/16/2018, 10:12 AM	#13
lpsouth1978 Registered Member Join Date: Jan 2007 Location: Arizona Posts: 915	WOW.... I apologize if my statements came off as argumentative, or like I was flaming anyone. That was certainly not my intent. I was simply trying to educate as to why the watts-per-gallon rule is not ideal. If it works for you, I have no problem with that, but it does not work in most cases (when talking LED's). __________________ Current tank: 40B work in progress w/20L sump

08/16/2018, 11:32 AM	#14
Misled RC Mod Join Date: Oct 2006 Location: Pittsburgh, Pa Posts: 11,440 Blog Entries: 11	They like to argue!!! __________________ Jesse I'm not saying I'm Batman. I'm just saying nobody has ever seen me and Batman in a room together.

08/13/2018, 06:10 PM	#3
dave540 Registered Member Join Date: Jul 2010 Posts: 70	LED fixtures are point source lighting to the extreme. Corals (sps in particular) can start to shade themselves as they grow. Sometimes this causes corals to grow in weird ways and sometimes the shaded areas die. Adding more fixtures helps reduce the shading in the tank and as a result corals can grow and develop more easily into large healthy colonies. Or instead of buying more expensive LED fixtures you can just add some t5s into the mix and save thousands of dollars in equipment cost. Give your tank the correct par and spectrum without the need to tinker with a controller. Sent from my iPhone using Tapatalk

08/13/2018, 08:37 PM	#4
Uncle99 Crab Free Zone Join Date: Sep 2017 Location: Ontario, Canada Posts: 2,906	Some LEDs are quite powerful and focused, I can't run mine more than 50%, just too bright. To much space creates a big drop in PAR.

08/15/2018, 05:20 AM	#6
LPS_Blasto Registered Member Join Date: Apr 2008 Posts: 581	I use a simple formula to calculate LED wattage. Old school rule of thumb (for me... your thumbs may be different... and may smell) 4--5 watts per gallon when using T5HO or Metal Halide. Thats good for most corals EXCEPT SPS. Anything else will do fine under that much light, and some may need to be placed lower in the tank. Typically works fine for tanks around 16--24 inches in depth. To convert to LED, simply divide by 3.7 100g tank with T5HO = 400--500 watts 100g tank with LED = 100--135 watts Your mileage may vary.

08/15/2018, 08:25 PM	#9
Uncle99 Crab Free Zone Join Date: Sep 2017 Location: Ontario, Canada Posts: 2,906	It's kinda like the 1 fish per 5g rule which could equal 10 tangs in a 50.