mfdrookie516 said:
LED's are not created equally. The difference in a crappy 1 watt LED vs a good 3 watt LED are enormous. LED's will work, just not those.
Thats only a 21 watt fixture, far too small in my opinion. And the blue to white LED ratio should be more like 1:1.
It's a matter of lensing and light output frequency, as well as LED wattage. For example, 50 2-watt LEDs with appropriate lenses easily equals a 100 watt high output LED in both total lumens as well as PAR, IF the color temperatures are equal. I have made these measurements and know them to be accurate. I am experimenting with the new 100 watt emitters, but don't like the color temperatures they are available in right now. When I can get them in a blue and higher energy white, I will start producing fixtures with them, otherwise I use 1, 2 and 3 watt lensed emitters for my panels.
But a LED fixture rated at 20 watts is only about as bright as a 50 watt MH, at best. And the mixture of 450nm blue LEDs with the +10,000K white LEDs is critical to the equivelant brightness.
Wattage, color temperature and lensing, these are what you look for. There is no substitute for total watts. LEDs produce almost twice as much PAR for the wattage than MH and almost no heat is projected, but they can't do the impossible. Rule of thumb, at least 2-3 watts per gallon of mixed LEDs to grow SPS corals in tanks over 24" deep.
On my 250 gallon, 34" deep tank I use 560 watts of mixed 50-50 high energy white and blue LEDs and have good coral growth. I use the same calculation for my customers tanks.
