Low lux but good par?

Murraydar · Jun 19, 2021

I'm running a reefbreeders photon v2 about 16 inches off the top of my tank. According to my seneye my par levels are fine (~100 on sand bed and ~250 near waterline) but my lux reading is around 10k. Running an AB+ spectrum.

I know lux doesn't matter for our tanks but the actual appearance of my tank looks super dim compared to others I've seen, especially ones with t5s / halides. Is that just a property of some led lights? I sometimes worry the corals aren't getting enough light but I suppose I should trust my instruments. Any thoughts?

redfishbluefish · Jun 19, 2021

Something doesn't sound right. @saltyfilmfolks has written a number of posts on use of a LUX meter, and with LEDs, found a correlation of LUX to PAR. For LEDs I believe the LUX range was 25K - 40K LUX. I actually target 25K and my corals grow like weeds.

Murraydar · Jun 19, 2021

Weird. I just retested to double check my numbers. 250ish par on surface with around 9k lux and 100 par on bottom with 4k lux.

Bpb · Jun 19, 2021

It’s the ab+ type setting and 250 par max that is making it dim.

Metal halide and t5ho bulbs have a significant amount of yellow and green relative to led panels which make the overall appearance substantially brighter due to the eye being more sensitive to yellow and green. With all channels set equal it will appear a lot brighter than with the ab+ setting which is blue/violet weighted

Murraydar · Jun 19, 2021

Gotcha. From what I've read lux is kinda meaningless in relationship to coral, so I'll just leave my lighting as is. I can live with the appearance, just wanted to make sure there's nothing actually wrong with my lighting.

oreo54 · Jun 19, 2021

Murraydar said:
Gotcha. From what I've read lux is kinda meaningless in relationship to coral, so I'll just leave my lighting as is. I can live with the appearance, just wanted to make sure there's nothing actually wrong with my lighting.

Besides the lux and blue thing MY opinion is ignore Seneyes lux readings. They are not accurate.

Blue example.
1000 lux of pure 450 nm blue LED is
115.55 ppfd ( par).