Radion Coral Labs A+B...intensity?

[boobookitty]

I have a 420G (96"x36"x28"), lit by 8 evenly spaced Radion G3 Pros. I switched from a 20KK emulation program a couple months ago to the Coral Labs A+B program. Things have been ok, but I'm wondering if my intensity is too high.

Lights are about 13" off the water line, and I ramp them up to 95% on the A+B program for 8 hours a day. Starting to wonder if that intensity is too high for how high the lights are mounted? PAR meter is broken, still trying to get it working, so I don't have readings; just wondering if anyone else is running that program at that intensity that close to the water line...

 

[dantdodge]

I have a 110 much smaller I added new sps every where.. Running the program you are I am using the radion mounts and I bleached all my corals at 43 percent dropped to 32 percent new corals adjusted quickly and started growing within 3 weeks I say all... but about fifty percent bleached in the intense areas and all frags were ten in above sand bed. All is well now I will finish adding all corals and once comfortable I will increase intensity..

 

[boobookitty]

Interesting. So with the radios mounts, how far from the water surface are the lights?

 

[Mr.Fishtank]

The RMS mounts the lights at 8 inchs i think. I used the radiant color setting. Had the lights hung 9 inches above the water and had the intensity set to 55% with a 40% acclimation for the first 6 weeks and never had any corals bleach or lighten from too much light. After the lights were done with the acclimation mode the par was 240-260 at my sps.
I was getting great color but growth was very slow. Probably could have turned them up a little but I switched to t5's. I think that 280-300 par at the more light loving sps would be an ideal range.

My sps were around 8-10 inches below water level.

 

[Mr.Fishtank]

http://ecotechmarine.com/wp-content/uploads/2016/01/Ecotech_CoralLab_WP1.pdf

 

[boobookitty]

Finally got the PAR meter running again. At the top most point where I have coral (5 inches below the water line, about 18 inches below the lights), at "high noon", PAR value is 410. So, yeah, seems high...explains why I'm having trouble keeping monti's alive there?

 

[Mr.Fishtank]

410 isn't really high but I think that the corals will do better around the 300 mark. Keep us posted and share some pics when they settle into the new intensity.

 

[boobookitty]

OK, so looks like PAR at the top line of corals (5" below water line, 18" below lights) is around 400, and PAR for the bottom line of corals at sand bed level (24" below water line, 37" below lights) is around 175. I'm going to lower the intensity of the A+B program from 95% to 85% over the next week or so, to get the PAR down to 325/100. Any other recommendations?

 

[boobookitty]

So, with the array of Radion XR30w Pros I have (2 rows of 4 across the top of a 96"x36" tank), I get the following PAR readings at the top coral layer, depending on intensity:

90%: 435
80%: 390
70%: 360
60%: 325
50%: 280


It's interesting (to me) that it's not entirely linear: 10% drops result in PAR drops from 30 to 45. Also, if I'm going strictly on PAR, since I was shooting for around 325, I'd keep the lights on 60% intensity, which just...I dunno, *seems* low.

Thoughts?