Are 2 250 watt XM's not enough?

[SueT]

Jim sold me on the XM's and I am now using 3 over my 180g sps tank. JB NY on RC did a lighting study that shows the X<'s are on 2nd. in PAR to the iwasaki. To me that says they have more than enough PAR to keep sps happily. Here is the link to that study: http://www.cnidarianreef.com/lamps.cfm This shows a lot of different 250w lamps run on different ballasts and the PAR reading each had.

I am really loving mine and I am now seeing coloration shifts that are for the better. My purple plating montipora is a purple/pink that the colors jump out at you. It is amazing.

[SueT]

Joshua, I'm definitely using the 10k XM's. I was afraid the 250w 20k XM's would be too much of a PAR loss from the iwasaki's. I was so happy to find out the 10k's are as high in PAR that things might not suffer. I also supplement them with 2 160w URI 03 blues. Shame on me as they are nearing 2 years and I have them on the list to be replaced next. They still kick a lot of blue out though.

[Derek B]

Thanks for all the input guys!!! I did not realize how much punch (PAR) I had lost going from the 65K Iwasaki to the 20K XM. I think what I am going to do is burn my 20K's for the remaining 6 months they are good for and then get the 10 XM's with 2 Actinic VHO's. That color combo looked the best of all in the study that Sue mentioned.