LED Comparison Question

[Galantra]

I am unsure if there are others just like me but, I am unsure what certain amount of LEDs would be equivalent to other light units example MH or T5s.

My main question is there a method used to find out whats the equivalent of certain number of LEDs would be equal to other units? Or is this not the case with LEDs. I know that there isn't many UV LED light units out there is there a benefit to getting one of these type units or single LED versus standard types?

I would like to do the switch completely but when ever I ask company, individual, or seller they suggest a brand or how many units or single LEDs (retro) I should get. It doesn't help me feel better, cause I tend to get the feeling it is not enough or will I have to upgrade lighting down the road again.

Why don't they create something saying these many LED or LED unit is equivalent to 400w MH or so on. Why just say the unit is 60w or 120w and you end up placing it in your tank and it cannot house SPS effectively like a T5 or MH could

Any insight on this anyone?

 

[adamt]

Ive heard Chris from reefkoi say that the evolution 120w pendant gets the same growth on his frag tank as a 400w halide. But the reason theres no generic direct comparison is cus leds vary quite a bit. lenses, wattage of the emmitters, heat sink and a number of other factors determine how bright an led unit is.

just as a staring point, regular chinese made 120w led with 50/50 blue and white using bridgelux 1 watt emmitters is roughly equivilent to a 250w metal halide.

 

[Galantra]

I understand what you are saying but how would someone that is new to LEDs or worried on result feel comfortable if you can tell in comparison to what you are currently using or use too?

 

[qy7400]

How are you trying to compare them? Lighting overall , IMO, requires a little homework as no 2 items are the same. Look through Sanjays lighting guide and you will see a 10K MH will have a higher PAR than 20K. On the far end a 400W Reeflux 10K has a PPFD of 85 on the CoralVue ballast where a 250W XM 10K has a PPFD of 115 on an IceCap ballast.
I'd have to go back to Grim on RC and get numbers for T5 but they jump dramatically from the bulb with no reflector/flat reflector to IceCap reflector to being over driven.
A 3W LED does not have to be driven at 3W. The manufacture can chose to drive them at a lower power to extend diode life and reduce heat or use an adjustable driver to allow the user to do this along with change color temp of the light. With optics a LED can almost double its PAR at 24", be over 1000 6 inches below the light but at 12 inches off center be almost non existent; this reason alone is why you see some raise the LEDs high off the water.

 

[adamt]

what are you trying to light?

 

[strgazr27]

Tank your tanks area in square inches and divide it by 15. This will give you a pretty good idea of what you should be looking at wattage wise to keep close to anything you want. Tanks over 18 deep you may want to add 8-10 LED's to that number or go with tighter optics for better penetration.

75 gallon:

48X18/15 = 57.6 or roughly 60 LED's (Assuming 3 watt Crees)

It's rough but it will get you in the ballpark...

 

[NL146]

Tank your tanks area in square inches and divide it by 15. This will give you a pretty good idea of what you should be looking at wattage wise to keep close to anything you want. Tanks over 18 deep you may want to add 8-10 LED's to that number or go with tighter optics for better penetration.

75 gallon:

48X18/15 = 57.6 or roughly 60 LED's (Assuming 3 watt Crees)

It's rough but it will get you in the ballpark...

What's your source for this info?

 

[Saltinmyblood]

There's a huge thread on rc with par testing and that's how they came up with the number of leds needed. I myself have a 90g 48x18x24 and I'm running 72 1:1 rb/cw 36 on each 6x16 heat sink (XP-Gs and XP-Es) with 40 degree optics mounted 15-16" above the tank. If I could do it all over again I would space the leds a little further apart or I may just take off some of the optics and lower them because the light is just a little too concentrated but I can dim them to what ever I want and get good coverage and spectrum.