Lighting for clams?

[CHEAPREEF]

So run the 400 at 20k and the 175s at 10k. Would that be a good combo? Would i still need actinics or would this be ok on it's own? The reason i didn't really want to do it this way was the heat issue, also electricity cost. I worked it out the cost should only be $3-4 more a month so big deal, just the heat. Any other draw backs?

Thanks
Clinton