["Umm, fish?"]

Thanks Avi. Three inches under the bulbs is what I'll aim for, then. At three inches, I ought to be able to aim a fan between the guard and the bulb, too.

I'm not only trying to block the UV (although my eyes hurt when I stare at tanks for a long time that have exposed pendents, so I know I need more than just a bare bulb). I'm also trying to place a splash guard and avoid the light shattering if it gets hit with any water (it happened to a guy I know). But thanks for your reply der_wille_zur_mact.