Quote:
Originally Posted by mr.wilson
What kind of PAR where you getting with the 10w emitters. I find 50w multichips are not bright enough for most tanks and I can't see 10w chips working for even a nano tank. The bleaching was probably due to spectrum (quality) not PAR (intensity).
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While I realize the 3 watt Cree emitters so popular today are more efficient than most multichips, your statement about not even 50 watt multichips being enough for some tanks might have the Cree diy'ers & even folks with Radions that use single chip discrete LEDs wondering?
My build uses 27 of the 10 watt multichip emitters (3 rows of 9) and hanging 6 & 1/2 inches above the water without optics they do just fine (4 foot, 77 gallon Hagen tank). I don't have a par meter & not an sps heavy system, but the coral I have (incl. montipora) is doing as well or better than under my previous MH/T5HO set up. BTAs are looking better than ever as well. Come to think of it, for months I've been underdriving my 10 watt LEDs since it's a somewhat unconventional build using constant voltage power supplies controlled by manual dimming. After doing some current measurements recently, I've cranked up the voltage but still below the 9-12 volt specified forward voltage for the emitters I'm using.
IMO it really depends on density (number of emitters), spacing, spectrum, height above water, optics etc. as to whether a certain set up is going to work well for any given tank. That could be 1 watt, 3 watt discrete LEDs or multichips of pretty much any size. The smd LEDs used to make a 10 watt multichip are essentially the same as those used to make the larger multichips. The big boys simply have more of them packed on to the substrate. Your pendants are mounted high with optics, my build is closer to the water surface with no optics.
Before embarking on my 10 watt build I also had a look at the larger multichips but was a bit nervous about how the emitters are crammed on to the larger chips. Obviously heat management is key or one of these is going to cook in short order & you're out a few $$$s. The 10 watt multis look to me to be well spaced with only 3 rows of 3 chips in a series/parallel arrangement. Seems to me that they are less likely to self destruct due to a momentary overheat issue, but that's just an opinion, although my set up has been running since April with no failures. A downside to the smaller chips is more wiring, a few hours with the soldering iron getting them all hooked up. Pros/cons either way, but as mentioned there are plenty of ways to make different LED configs work these days with even more on the horizon.