Lighting Advice please on these LEDs

Need to see some PAR readings to judge the intensity. Pics are the worst method for others to tell by, especially pictures of LED lit tanks. I use 48w of LEDs over my 4' 60G tank and it is more than enough, but it is also DIY so the light is spread out more and has the proper height/optics to perfectly cover the tank.

 

I put some PAR 38 LED lights over my tank. I found that I needed to change the lenses to spread the light out somewhat.

The light is strong enough. If you have a mix of blue and white, they seem to not be as bright, but really are - in the direct beam. The PAR drops off dramatically as you get away from the center of the light beams.

 

The problem with those lights, as you discovered, is by custering LEDs in a PAR38 bulb it creates really bright 'hot spots' in the center and then tapers off dramatically. Under the bulb you may be seeing 200-300 PAR, which is perfect for LED light for just about any coral, but you move 4" off center any direction and it plummets down to 20 PAR, which is barely enough for mushrooms. Clustering does solve the 'disco effect' problem, so it isn't a bad thing, just requires a slightly different approach than LEDs that are spread out. I use 40 (on the 4 LEDs at the ends of the fixture) and 60 degree optics on my LEDs, and my light is mounted 24" above the tank. 60 degree is as wide as I would go unless you plan on adding a lot more LEDs. Once you start using 80 degree optics, the intensity really drops, but the spread goes up. So your 200-300 PAR reading with 60's will now be 100-150 PAR with 80's, depending on the height they are mounted above the water. It is a balancing game for sure.

I do think you will require 3 PAR38 bulbs on that tank to adequately cover the entire tank with the proper intensity, no matter which optics you go with.