lights

[mr_alberta]

A lot depends on the depth of your tank and, obviously, the inhabitants you want to keep. I wouldn't go out and buy, say, a 400W MH fixture for a 20" tall tank, but that's just me. Also, I've seen many beautiful tanks lit only by PC's or VHO's (the VHO one has been running for about 7 years now).

I would consider possibly adding another one of your 4x65W PC fixtures or a couple of VHO's as it will probably be cheaper for you to add more light rather than trying to sell your current fixture (which, if you bought new and locally, probably paid 2 or 3 times too much for) and getting a dual MH fixture. This will, however, limit what you can keep in the tank as well as where in the tank you can keep it.