First Post; LED lighting question

[RabidWombat]

Hi everyone,

TL;DR: Is there a general rule of thumb to calculate the number of LEDs needed for a vivarium based on its size?


I am planning to start a build within the next one to two months for Vietnamese Mossy Frogs. I've got an old 36x16x10 tank that I am going to use. Currently, I'm planning the lighting and will be purchasing this week. This will be my first LED build. I've been tinkering with them for a while for another project, so I'm not entirely new to LEDs. What is new, is using them for plants/animals.

I'm going to go with CREE XM-Ls; cool white and warm white. These seem to have decent coverage in the spectrums that encourage photosynthesis. They also appear to have higher light output than some of the similar LEDs.

My biggest question right now is figuring out how many I need to keep the plants healthy. I've found formulas related to reef tanks but not for vivariums. What is really throwing me off is the info I've seen suggests using a very high number of LEDs, 45-60, on tanks that are not all that much larger than mine. I can see needing more lights when water's involved, but is a similar number necessary for vivariums?

With the dimensions listed above, does anyone have any suggestions? I'll be using 40° optics, approx 4.5" above the top of the viv. Based on this, I can get full light coverage with three sets of lights; 7" from the left and right sides and then one set right in the middle.


Thanks,
RW

[deranged chipmunk]

i'm not exactly sure on the calculations, but you are pretty close with three sets. the numbers for reefs and planted tanks take into account diffusion of light through the water column. par is diffused rather quickly through water, but not through air, so i think you could probably get away with 3 sets, especially since you'll be using the 40 degree optics. that's a nice spread for an LED

[RabidWombat]

Great, thanks! I think it'll work out well. I went ahead and ordered the 3 sets and popped one up with the optic to test the light spread. I think it's going to work out well.

Thanks for taking the time to reply to me. I really appreciate it!

[yuri258]

LED Lighting? Is it proper to discuss this question here in this forum?

[UncleChester]

LED Lighting? Is it proper to discuss this question here in this forum?

Yes this is the right forum for lighting questions, RabidWombat put it in the right place. What is kinda weak imo, is a brand new account popping in attempting to be subtle about the LED lighting they sell with an innocuous question about whether this is the right place to ask about LED lighting. At least make an attempt to add some info here. If you sell LED's and have some experience in their use in terrariums I'm sure everyone would love to tap that know-how.

[DiggenEm]

I dont know how many LEDs you need, but a light guy on the other board told me that its all about the lumens and that 2k lumens per enclosure is optimal. Of course i know this is dependent on enclosure size.

[RabidWombat]

Thanks Brian and Digg!

I've just about completed the light. Being new to this, I made a few mistakes. It's been fun putting it together. I'm out of town right now. Next week, I'll post up some pictures and some things I learned while doing this.

RW

[deranged chipmunk]

Cool. I was going to ask how you made out with that project. Were the 40's good?

[RabidWombat]

Sorry for the late reply. I've been out of town a few days.

Here are some pictures. The 40 degree optics will work great for this particular tank. It's 36l x 18h x 12d. I'm debating going with a 40-gallon breeder instead (while they're still on sale!). If I do that may pose an issue for the 40 degree optics, but I haven't really spent any time on that yet.

This was my first light build, so it's not the prettiest thing ever, buuut I'm mainly going for functionality and a learning experience. A lot of this build was done on-the-cheap. The hood is a plastic rain gutter, fans and power supply from the swap meet, and heatsinks from a local electronics resale shop..


Here's 2 of the 3 sections in the hood. They're spaced equally to give overlap and cover the entire tank. You can see the fans at the end. I picked these up for $3 each at the swap meet... they throw a ton of air but are very loud. I am probably going to go with low-profile fans and mount one directly to each heat sink.


Close up of the one heatsink. There are two 6500k (cool white) leds and one 3000k (warm white) led. I really like this combination. I put a few items in under the light to test and it looks great. They're also close enough together that you can't tell that there are two different colors.

Each heatsink is wired individually. I can easily take things apart as I am working. I am glad I did this. I found a mistake in my volts-to-driver-to-power supply math. The LED driver I got (buckpuck) will support a 32v input and will output whatever is input MINUS 10v, so 22v output. I missed that MINUS 10v part so I can only run 6 LEDs from my one driver. I'll have to order up another one.


Here's what the hood looks like on the tank. I'm going to clean it up a bit. At the least I'll just paint the bolts white so they match. Otherwise I may do something else like make a cover for it.


$5 swap meet special... Gotta love it. Power supplies are expensive! This may not be the best solution, but while trying to figure this stuff out it's great.

[RabidWombat]

Here's two more photos so you can get an idea of light output. There's no light in the room except for that these are giving off.

This is my dive torch. I use this as my primary light when scuba diving at night. It's got an output of 400 lumens:

Shockwave LED | Princeton Tec



Here's one set of the LEDs for the enclosure..



And if you're thinking "Why does he use such a weak-sauce light for diving??" Well, I am planning to build my own dive light... eventually. Gotta blind some fishes!

[deranged chipmunk]

nice job! i've never done a diy led. have read a lot of threads on it from another forum, but never actually dove into it. i like the rain spout idea. i would have gutted a shop light, but i like the plastic idea better.

and i thought i was the only psychopath who worked on electricity around water???LOL

[RabidWombat]

and i thought i was the only psychopath who worked on electricity around water???LOL

I think it's a sign of genius.... right?

[deranged chipmunk]

yeah, let's go with that.....LOL