Quote:
Originally Posted by lsouth913
I'm really wondering on the wattage going with led.. do you need the same wattage as say mh 3-4w a gallon? Or do you have to check par with your setup and adjust power on the led?
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IMHO wattage and lighting for an aquarium is
really an out of date idea (and it was never a really good system even back in the days before led lighting). I think any currently available led aquarium fixture using 3 watt or 5 watt leds is going to be strong enough that you probably aren't going to run it at full power anyway. On average I'd say that even a cheap Chinese black box 16" 165 watt fixture (55 leds rated at 3 watts each but only driven at 2.2 watts) used to cover roughly a 30"x24" footprint in a 24" deep tank will be run between 50% and 80% of it's total power output (with the blue channel at 50% to 100% higher level than the white channel). I run mine with blues at 90% and whites at 40% or less.
There are fixtures like the Current Orbit that use 0.3 to 0.5 watt leds and try to make up the lack of watts/led by using a lot more leds per fixture. That does work as long as the water depth is shallow enough, about 16" max on average (a bit less (12") for sps and a bit more (20") for zoas and softies). The issue is theat more leds can not make up for the lack of depth penetration of the light. A Current Orbit fixture at 100% power has a PAR of 50 or less at 24" deep (according to their own advertising). A165 watt black box will have a PAR of about 100 to 150 at the same depth.
The best way to know you have the proper amount of light is with a PAR meter. They are becoming more common in the hobby and even better accuracy than when the Apogee meter hit the hobby about 8 or 9 years ago. The cost of a good meter is now about half of what an Apogee meter cost back then. And some people even rent them out. I loan mine out to local club members all the time in exchange for a coral frag or two.
The only other way to know, is to do slow acclimatization or use the 'canary in a coalmine' approach. Get a small frag of a red cap monti or any other inexpensive plating coral, and set it in your tank as high or higher than all the other corals. Start your acclimatization at a low number and raise it every week. You can raise it a bit faster early on, but get much more careful as you get up to higher power levels. When you raise the light intensity too high, the red cap will start to bleach before any other corals. At that point, dial the power back a bit (5% to 10%) and you should be good to go.