They actually aren't producing WH 7 ballasts right now. You can still get WH 8 ballasts, which are virtually the same. 1 1/2" longer is all. Although you can run 2 48" VHO bulbs on both the WH7 and WH8 They are not running at true VHO power levels.
Here is the RC link that talks about it.
http://www.reefcentral.com/forums/sh...hreadid=514658
Cheers,
Al