Amount of LEDs for nano diy

[Myke]

Wondering what the appropriate amount of leds or lumens for my 7g nano cube (12x12x12) would be? I have 1w and 3w leds already that are around 80-90 lumens per watt for the white 1w, 160ish for the 3w and 50 lumens for the blue 1w. Also have 30* and 60* optics although i dont think they are needed in such a shallow tank? I plan too for now atleast keep the stock 18W power compact installed in addition to the led upgrade. Would 20 leds too much?
Want to be able to grow any kind of corals, just dont want it to be overkill.

Also as far as light spectrum would it help to add a few red, green and warm white to make a mix of colors?

 

[unibob]

Are you going to have a dimmer? If not 20 led is way to many IMO

 

[harleymike]

I have 9 over my 15 gallon tank. Dimmable

 

[Myke]

Thank you both for the quick replys. No dimmer yet, going to get one later. Was hoping to run more leds that way I could add more variety of colors. However should have said there going to be running at about 20% under power, my lowest power driver i have atm runs 9-12 of the 1 watts. That would be enough?

Was thinking
5 cool white = 300 lumens
5 "royal" blue = 150 lumens
1 red = 25 lumens
1 green = 30 lumens

Look okay? Or should i use the same but with the 3w's

 

[Boga]

Hey Myke.
What LED brand do you plan to use and what drivers? If you use Rapid LED, you can use their calculation http://www.rapidled.com/led-university-1/. I think their calculation (Length x Width) / 18 is based on 3W LED's.

This is just a personal preference: I would change 4 cool white and 6 royal blue. Maybe I would add 2 UV LED's.

 

[Myke]

Boga - thanks for the link. Very helpful!  Calculator says 8 however Im using generic chinese leds and drivers. Not close to the power of bridgelux or crees but they were cheap. Playing with the leds last night i realize your right about the extra blues, looks better. Wanting for a small driver (3-5 leds) and some uvs now also.

 

[Boga]

I tried to do a comparison between lumens reported on Cree led's and your values. It looks that you may need at least double the amount recommended by Rapid Led's formula.

Example: one Cree LED CREE XP-G R5, at 1A, with a forward voltage of 3.15V. Power = 1 x 3.15 =~ 3W, luminous flux is 348 lumens.

And by the way: Welcome to The Frag Tank Forum.

 

[Myke]

Thanks Boga for the info and the welcome. Whenn i first order these leds i figured Id need alot more of them, but the cost is alot less. I will try double see how it goes.

Btw - can anyone recommend a good uv led? The chinese ones like i bought in the other colors are so much more I figure I should look for a proven brand.

 

[Boga]

Many folks are ordering from rapidled or aquastyleonline or ledgroupbuy.

I am using http://www.rapidled.com/violet-uv-led/ and I am happy with it.