I doubt you'll find a direct replacement. Your best bet, IMO
, is getting a stand alone fixture. If you really want something covering the tank, glass tops work well under fixtures. Are you doing a reef or planted tank?
"What, exactly, is the internet? Basically it is a global network exchanging digitized data in such a way that any computer, anywhere, that is equipped with a device called a 'modem', can make a noise like a duck choking on a kazoo." - Dave Barry