Let's get this project underway.
I graduated from college last week and finally have a few weeks to relax before I start grad school in August. This is one of the projects I have been putting off for far too long so I want to get started.
Here's what I have so far.
I'll be building an LED fixture for my 29g planted. The lighting will be mounted 24" above the substrate (the tank is 18" tall and another 6" should be enough for the casing and for me to have access into the tank). I will probably build a housing similar to what I did for my 55g AC tank but may need to come up with a way to cool the LEDs.
(I'm in the process of painting the wooden fixture casing black. It's looking pretty darn good!)
As for LEDs I am trying to decide between the XM-L2s (highest end) and XT-Es (replaced XP-G). Here are the specs that I could find. I will probably keep it simple and only go with the color Cool White (~6500k)
XM-L2 - Wattage 3W-10W, Max I - 3000mA, Forward V @ 700mA = 2.9V, $ 8.77
XT-E - Wattage 3W-5W, Max I - 1500mA, Forward V @ 700mA = 3.0V, $4.50 (solderless) $3.77 (Reg)
Using the Excel Sheet on Hoppy's thread I calculated out a couple of options. Here are the basic parameters I used. The only parameters I modified were number of Rows and Distance between LEDs.
Lumens per LED = 300Lumens
Height = 24 inches
Cone Angle = 40(deg)
Adjusting the spacing between the LEDs (# of LEDs per row) and the Number of Rows we get the estimated par level. My goal par would be somewhere between 40 and 70 (I believe this is adjustable from lowish to medium-high lighting)
From a little trig, if I had a 15" heatsink mounted 24" above the substrate (and centered in the tank) it would be a 17deg angle from vertical to the corner of the tank. It would be 51deg from the edge of the heatsink to the corner of the tank. 40 degree optics would nearly fully cover the tank (nearly).
# of Rows = 1
Spacing of LEDs = 3" (5 total LEDs)
Estimated Par = 63
# of Rows = 2
Spacing of LEDs = 5" (6 total LEDs)
Estimated Par = 45
I'm not sure what other combinations would be a good option. Any suggestions are welcome.
In both cases, how would I construct a heatsink? In the earlier posts (for the 10g) Hoppy suggested a 10" x 1" heatsink (i'm guessing that means 10" of the 1" heatsink). Would it be a better option to do two separate clusters mounted 1/3 of the way from each side, one large piece, or two channels (for the 2 row piece)?
1) Which LEDs would be the best option? Is it worth it to spend 2x the amount on the XM-L2s?
2) Which would be the better option for LED placement?
3) Would the fixture be better in two clusters on smaller heatsinks or one large heatsink?
4) At what point must I start considering building in a fan for cooling?