I'm using two of these lights for ~1.5 years, so far so good. It's on NUVO 20 gallons.
As you can see I have a few SPS frags, but, honestly, they were growing very slowly (doubled the size for all that period) and in strange patters. So, I decided to start tweaking the lights, shifting to warmer spectrum and noticed some increase in growth. I honestly didn't know each channel contribution to photosynthesis and could only guess. I was afraid to use too high values for anything as I have a bad experience with burning corals under Kessil. So, I was running both lights only at about 30-40% each channel, except Red (0%) and White (~4 times less than others).
Eventually, I decided to buy Seneye Reef Monitor to use it as a PAR meter. I know, it's not very precise tool, but better than just a naked eye.
So, today I've received it, did some measurements and I was shocked. Where my Stylophora is at the highest position (~6") I get only 80 PAR. And other corals below get even less. I didn't clean the lamps for a while, to be honest, and also the light goes through the NUVO's canopy, which scatters and absorbs some light. So, I've decided to measure what will happen if both lamps are at 100%. It was ~260 PAR at the Stylophora level, just about right. That's my goal now - slowly, week by week increase the brightness and see what happens. At least I'm not afraid of reaching that 100% level now. The giant frogspawn needs to be moved though, of course...
Also, to figure out a contribution of each channel, I did some separated measurements underwater:
(2 lamps!)
Channel______________________PAR
ALL at 100%__________________260
Red (called "Pink"
)_______11
Cyan__________________________9
Blue__________________________62
Violet (called "Purple"
)___22
White________________________172
I also did some more measurements in the air, fixing one (!) light between two chairs and putting the sensor 6" bellow it. Here is a table I put my data into:
(1 lamp, no water)
Channel_______PAR____LUX____PUR
All at 100%____184____6778___72 %
Red____________7______223_____83 %
Cyan___________6______181_____70 %
Blue___________44_____1577____84 %
Violet__________17_____596_____92 %
White__________120____4380____64 %
So, it's clear how much contribution the white channel has! I thought it's only bright to eyes, but it is actually very high PAR and even though the PUR is lowest, it's still the biggest contributor. It's temperature (white only) is ~7400K, btw. The PAR values are not far from the ones on the box, considering my lights are 1.5 years old and I didn't clean them)
I've also measure my old Kessil 160, just for fun. But reading were very strange. At 6" it was giving me crazy high values >300 PAR and just an inch lower it was almost twice smaller. At minimum brightness, I think... But that's probably expected for a point light, as brightness somewhat proportional to 1/R*R. That's why you have to keep Kessils far above.
My conclusions:
1) To grow corals (LPS or even SPS) you need a least two lights, which is still a cheaper option than buying top brands.
2) You have to use a lot of white to achieve high enough PAR for SPS.
3) The lights are great for shallow tank, but might be useless for too deep cube-like tanks, as they don't seem to have good penetration (very scattered light).
Overall, they are great lights and I'll keep using them. Let's see how long they can last)
