You guys might want to check out the mothership LED thread:
http://reefcentral.com/forums/showthread.php?t=1678127&page=43
It covers a wider range of topics, while this thread is mostly concentrating on the DIY driver project.
Does anyone know how many leds would be needed for an 80 gollon tank? I'm not sure what kind of corals I want yet, but I would like to have enough light to keep anything I want. Everything I check out doesn't give a basic rule of thumb to how many leds are required for applications. I have a friend that said he thinks his 12 leds are equal to a 150w MH. I'm not sure this is true, but his corals seem to think so. This is the kit he bought
http://www.rapidled.com/servlet/the-35/12-Premium-LED-Do-dsh-It-dsh-Yourself/Detail
Is this a good kit? I have NO experience wiring up lights, so this easy kit seems like a good purchase for me. I've seen that these are the same type of leds that everyone seems to reccomend, but I just don't know how many I need. My main concern is power comsumption. My electric bill is high enough and I don't want to watch my meter spin every time I turn on my lights. Thanks for the help guys.
That's an OK kit. Some of rapidled's kits use the Q4 bin cool white XR-E, IMHO you want to avoid those. But this kit uses the better Q5 bin. However, it uses a less-versatile driver. Meanwell also makes a driver called the ELN-60-48 that allows for dimming, while the one in that kit does not.
For your 80 gallon tank, you might want 50 - 75 LEDs. It'll depend on the intensity you want, drive current, optics, etc. But it'll be a vastly smaller impact on your power bill than any comparable lighting, no matter how many you use (within reason of course).
Regarding your friend's comment about 12 LEDs comparing to an 150w MH, it's hard to make generalizations like that, but if you drove them high and used moderate optics, and were comparing to a poor or average MH lamp, that would probably be a fair comparison. In general, you can assume a LED rig will be ~40% the power of a comparable MH rig.
Anyone know how many buckpucks/leds you could run off of a 24v 8.3a power supply? I know I have seen the math somewhere but this post has become too large to search through. Thanks for the help.
You're probably thinking of the mother post I linked above. For reference, a buckpuck running at 24v with 6 LEDs can be assumed to draw about what the output current will be. This is a rough estimate, because - being a buck driver - it'll actually need LESS current than the output current, the difference depending on the drop in voltage it has to create. However there will be a ~10 - 15% efficiency loss, which is usually about what the drop in current is, so it ends up being about an even tradeoff. So, if you're driving at 700mA, you can assume each buckpuck will draw about 700mA.
Now, just multiply that number by the number of buckpucks you want to use, and add 20 - 30% for some headroom (power supplies lead short, hot lives when pushed above 70 - 80%). Or do the math the other way - cut 30% off your power supply's rating and divide by drive current. So, for your 8.3A supply, you can happily load it to 6 - 6.5A. That's 8 or 9 buckpucks at 700mA. In the end, the power supply ends up being one of the cheapest major components in a build like this, so IMHO it's safe to leave a good head margin like this vs. loading them to the hilt.
EDIT - jma beat me to the punch by 7 hours! That's what I get for opening a thread at night, leaving it open, and replying in the morning without refreshing.
