DIY LED help

[makana]

I'm having a hard time understanding how to decide the number of LEDs needed for a diy fixture. There are lots of formulas floating around for it but it seems most people end up dimming their fixtures way down around 50% which leads me to believe they could have gotten away with less LEDs.

From what I gather the formula for figuring out the light spread is tan(degrees)*distance. When I do the math the diameter of the beam is huge even with 80 degree optics. I found an online calculator that says with 80 degree optics the beam is 13.43" only 8" from the bulb and 33.6 at 20". Does that seem correct?

[The Grizz]

In theroy you are correct but the further away from the source of the light the weaker it's intensity. In order to get good intensity out of any led you want the beams to overlap this also helps blend the colors more even.

So the taller the tank the more LEDs are required is my opinion to get a good intensity.

[makana]

So if that is accurate then two LEDs with 80 degree optics already covers more area than needed as far as distribution. So then how do I figure out how many are needed for intensity?

Why is the LED spacing recommendation 2"? If the spread is that wide I'm not sure why there is even any need to spread them out at all.

[The Grizz]

Not sure how it's calculated but I think Martin @ Modular LED has a way to calculate it.

If you look at a SOL fixture they have 8 pods of 3 LEDs each ( 1 - white, 1 - blue & 1 - royal blue ea. ) & each sol is sufficient for 24" x 24" roughly. If you look at my DIY build you can see what Martin & I came up with for my 8'er. Each heat sink covers 4' obviously & it's reccomended to have 6" difference on all 4 side between tank & heat sink.

Oh and just for reference I built my LEDs to suit my up coming 300 gal 8'er ( 96" x 24" x 30" )

[makana]

Well the two things I'm struggling with is the intensity and distribution of the LEDs. The AI nano is quite small and almost seems to be a spotlight. I could go the PAR38 route but they always look like spotlights. So I want to distribute the LEDs over a large enough area to not have spotlighting.

The intensity issue is less important. I will go dimmable so I could always just turn it down. At the same time I don't want to end up like others have where I can never turn up the light beyond 50% without cooking the corals.

[The Grizz]

What size of a tank are you putting them over? Where are you getting your LEDs from? I know that both Modular & Rapid LED have reccomended amount of LEDs for the size of your tank. It helps take a lot of the guess work out of a DIY build.

[makana]

I had been looking at Rapid LED. I guess I will just use their formula. I was just hoping to gain some understanding on where the formula comes from and if it is accurate.

The tank I was planning for is a 20 high. The other issue I had was the size of the heat sink. I was thinking of going big so that I can distribute the light evenly but most of the lights you can buy are smaller so the light is mainly focused over the centre of the tank.

[The Grizz]

I will be talking with Martin tomorrow and see if he can shed some light on the subject for both of us as far as number of LEDS.

As far as your heat sink personally I would make it 12" shorter & 12" narrower then your tank. Anything bigger you will be shooting light past the edges of your tank which would be a waist.

[makana]

Thanks alot. Let me know what he says.

The tank is only 24x12. So do you think it would work if I made it like a strip light? I could go 12" long and an inch or two wide. If that would work I could probably fit it in the old freshwater light.

I was thinking that I needed to make the heat sink only a little bit smaller than the tank to get proper coverage.

[pinhead]

There is an excel spreadsheet that does all the calculations for you. Type in your dimensions and it tells you number of LEDs, colour combinations and even cost of Crees at todays prices. I just checked and prices were updated today January 15th


http://www.nano-reef.com/topic/304152-led-lighting-calculator-i-update-the-file-um-semi-regularly/

[The Grizz]

Thanks alot. Let me know what he says.

The tank is only 24x12. So do you think it would work if I made it like a strip light? I could go 12" long and an inch or two wide. If that would work I could probably fit it in the old freshwater light.

I was thinking that I needed to make the heat sink only a little bit smaller than the tank to get proper coverage.

So after talking with Martin today there is really no way of calculating the intensity ( par ) before you build only after its together & running, then you can check it with a par meter.

Well if your 24" x 12" I would go with a 12" x 4" heatsink, use rapids reccomendations but order a few more just in case you want to add a few. I would suggest 8 whites, 6 blue & 6 royal blue for starters.

[The Grizz]

According to the formula on Rapid Led you would require 16 leds over your tank. I would still go with a few extra just in case. If you dont run them at 100% they should last longer i would think.

[makana]

Thanks for all your help! I find the entire topic to be a little too much like trial and error and really lacking in available information.

What are your thoughts on the cool white vs neutral white. The neutral white looks to cover more spectrum so I was leaning towards that. But having never seen the two myself I don't know what they actually look like. I'm hoping to get close to full spectrum but don't want it to look bad.

How about optics? I have read that you don't need optics on a tank under 24" depth. I read a contradicting article that said you need optics to achieve the equivilent of 150w mh regardless of depth.

[The Grizz]

It is a deffinate gray area for sure.

I didn't like the color of the Nuetral White in my build & have changed them all to cool white, much nicer color mixture with the blues. Nuetral whites have a bit of a yellow ting, where as cool whites are a nice clean white.

As for optics, as far as I'm concerned there are very much needed for all colors except for reds & green. Optics focus the light from the led downward instead of outward. Also any blues used for moon lights don't need optics as you just want the light to spread out wide.

[makana]

If I understand the math correct 60 degree lenses would give me a 34" diameter 20" from the bottom and almost a 14" diameter 8" down. So If the light is 2" above the water there is still great coverage for my size of tank. From what I have read it sounds like 60 degree optics should match 150w mh.

So given the size of my tank, without optics the colours I add for full spectrum should be ok if I put one of each in the centre of the light. I'm thinking one of each without optics: red, green, violet, and neutral white. Then cool white and blue/royal blue with 60 degree optics running down the length of the light.

Does that sound good? Do you think the 1.8" x 12" heatsink from modular led would be wide enough?

[The Grizz]

I would give yourself more room to spread out the LEDs more, it would allow you heatsink to dissipate the heat much better. If you have an old fixture housing you want to use go as big as possible & don't skimp on cooling fans to blow on the heat sinks, heat is an led killer.

[Ct_boi]

Hi guys I am setting up a 20g tall nano reef and wondering if anyone has used or know about aquastyle LEDs.

[The Grizz]

Hi guys I am setting up a 20g tall nano reef and wondering if anyone has used or know about aquastyle LEDs.

Heard of them but never really look that hard at them.

[Ct_boi]

I've been looking into them allot and have noticed some good reviews. However I would like to know the type of custom price friendly LEDs most reefers are building. Please help. Thank u.