What's the age/condition of your ballast? I'm running one radium on an electronic ARO ballast, and it is very bright, not overly blue at all. I have it over a 40br and have to have it on an inefficient spider reflector to keep the par from being too much (think I'm getting about 200-250 on the sand, iirc). Do you have a par meter or can you borrow one? FWIW, the xm10k on an m80 will crank out 2x the par of the radium, so I certainly wouldn't replace both with xm10k. I used to run a 250w 20k plusrite on an m58 ballast with two 36" VHO bulbs over a 58g. I could easily grow sps in the far corners.