I'm looking to figure out how many watts of LEDs I would need to have them suspended 1ft over a 36x24x18
Never Judge The Intensity Of A LED Fixture By Watts!!!
These are just some of the factors that are very consequential in the final Intensity per Watt
-LED Type
--Cree and Luxion Three Watt LEDs can be twice as bright as Generic Three Watt LEDs at the same drive current.
-LED Drive Current
--Just because its a 3 Watt LED does not mean its driven at 3 Watts.
--I prefer to drive our 5 Watt LEDs between 2 to 3 Watts to maximize efficiency.
--The Harder you drive an LED the more Heat and less Light it produces.
-Optics
--Some optics are only 60-70% efficient were others are close to 90% efficient.
--Optics are a Force Multiplier focusing the light where its needed and not to the sides.
--Proper use of optics, angling the fixture and height adjustment can double the intensity while reducing the spill.
Thermal Management.
--This is some what related to drive current as the cooler the LED is the brighter it gets.
--Avoid Fixtures that are "Hot To The Touch. Heat is the enemy of any electrical component.
Here is a 24" depth PAR Graph of an optimized 118 watt LED Fixture. I like to see at least 200 PAR on the sand bed for clams and carpet anemones. Also for SPS having the right spectrum and intensity leads to the development of pigments which reflect this extra light.
PM Sent
Bill