OK, I guess I " could " get 12 - 72" VHO's (165w each) on a 210G tank. That's 1980w of VHO over that tank. 9.42 watts per gallon a little too much I be thinkin !! (considering I don't want sps or clams) Somehow I don't think that would be better on my electric bill than the 3 - 250w MH's and 2- 60" vho's (110w each) I had on the 125G ..... probably not much cooler temp wise either.
If I ever get this tank going, I don't want the heat issues I had with the MH's. I could always buy a chiller....just don't tell my hubby what a chiller for a 210G tank costs and I may live to tell about it, but I doubt it