400 watts halides

I thought he still had the 3x250s at the time of the pic...
Oh well.
Back to the show....

 

Yeah, the pictures above were when he had 3x250. Did I accidentally say otherwise?

 

my 75 g ( 21" h ) runs 2-400w se mh (sps 14k ) with 4-65w pc ( coralife ) using e-ballasts and lumen bright reflectors that houses nothing but sps's with 420 par on the sand. the top of the rock is 12" from the top of the water, if i had the rock structure was closer to the top of the water then the 400's would be to much no matter what the coral and the 250's would be used. on a higher rock structure the par values have a wide range from top to bottom and the 250's would be used then the lower light corals would be at the bottom and the light loving corals at the top. with the 400's and a flat rock structure the par values are close throughout the tank. the 250's would not produce enough par to house sps's on the bottom of the tank. in general the higher the k value the lower the par, and not all 10k produce the same par. there is so much that goes into this conversation that this single thread cant cover everything.

basically the rock structure and corals will dictate the amount of light.

 

420 par at the sand bed?? What do you have at the top? For a mixed reef tank, that much light is really too much IMHO. But I let the corals decide that. Most lps don't like more than 250 or so at the bottom, and many sps do well down that low.