What's the highest PAR you've grown your chaeto at?

[duberii]

I just bought a light that claims to output 330 PAR from 20" away (in the air of course)- I plan to hang it closer to 10" away, so using the inverse square law I can probably expect around 1320 PAR. I know that natural sunlight at the surface of the ocean can reach around 1500 PAR, so I'm not too worried about killing the chaeto. However, I do want to know, in the case that I have to lower the light, if the chaeto will suffer. I've read people saying they have grown chaeto under sunlight supplemented by 3 metal halide bulbs, so I can't imagine that overlighting is an issue with chaeto. What is the highest PAR (Estimated or measured) that you've grown your chaeto at?

 

[andrewey]

The only time I measured the par of my cheato on one of my old refugiums, I was hovering around 300 or so. I'm guessing my current one is much higher, but honestly, I don't know that to be true. That being said, there are some threads where someone had testing their H380, and if memory serves me correctly, it was something ridiculous, like 1500-2000, 1" below the surface and 1000 a few inches down (I believe the light was situated a few inches off the water).

Honestly, I wouldn't worry about the par per se, just the acclimation of the cheato. I've grown cheato under everything from spiral CFL bulbs to some pretty intense LED multichips. So long as I was mindful to acclimate the cheato slowly to the higher lights, it always grew well.