In the context of my tank, I keep PAR values between 300-500 mmol/m2/sec for those Acros that require high light. So-called deep water ones get between 200-250 mmol/m2/sec PAR.
Here is a recent photo of my tank:
No idea what my PAR is. I thought PUR was more important than PAR? Here's my reef with 8x54w 10hrs with 1hr ramp up either side:
I think the photo period is also important to consider. The less PUR there is available the longer you want your lights on. Imo SPS can take either short strong blasts of light (4-6 hrs) or less powerful lighting for a longer period (8-12 hrs). As long as the energy they receive is within the limits they prefer then its all good. Some will grow better with higher light, some better with lower then you have to consider coloration which is a whole new ball game!
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Ed the Coraline on your overflow, I am guessing that's what it is, looks like cake layers that need to be chiseled off
Dana's talk involved him pushing the idea that too much par was bad for our corals right? If I remember correctly he said lower par is better than very high par. I need to watch it again but I didn't get to much needed info from it last time so I may not.
I think the more par the better, but this is in relationship to nutrients going into the tank. Not nutrient levels on a test kit. If you feed healthy foods all day long and keep adiquate flow there is no light that will "over light" your acros and the more food and light the better, given its a good source of light and for the right amount of time. Which is another aspect to this conversation.
