The skinny on PAR

[asylumdown]

I know I'm being lazy and that this information is out there in a myriad of places, but maybe if I toss it out to you guys my question can be answered with a single keystroke...

What is a 'good' PAR reading? I hear people talk about fixtures putting out '200 PAR at tank bottom' or '380 PAR at surface level', etc. etc., but what exactly does that mean? What PAR rating is acceptable for what type of coral? Will SPS grow under 200 PAR? Is there a golden number we should be aiming for at certain depths?

[chris88]

there is a lot more to growth then par but for sps the range is 500-200. some sps need a but more some can do with less. sometimes growth will get so out of control that the large corals will shade itself out or other corals. just because someone has a lot of light intensity doesnt mean good growth. ia hev seen tanks with powercompacts grow coral very well and tanks with mh not grow corals at all. But to answer your question 200-500 is the sweet spot for par.