I have a Coralife Deluxe Aqualight (4x65w bulbs) on my 90g that I've replaced bulbs on recently - Shango, you will be ecstatic to know I got my replacement, 55w, 21" straight pin 6500K (same as original K) bulbs for $9-something each on elightbulbs.com. They fit the fixture perfectly and were much more cost-effective than the Coralife brand. So far no difference on plants so it seems the output is the same (though I certainly noticed the new bulbs were brighter than the old!) As long as the wattage of the new bulb is <= the max wattage of the socket there shouldn't be an issue. I spent months looking for the cheapest replacements out there, so trust me on this one! They also have other K ratings available if you prefer cooler or warmer. I got the 6500K because from everything I've read it is the most ideal for the plants. Now, if they only had my 50-50 quad tube for the SW tank I'd be set! Sad to miss so many meetings recently. I keep forgetting they're coming. Plus I don't need the temptation to take anyone new home since the 90g was diagnosed with TB. I'm being good and letting the tank get empty so I can start over, but it's not easy. On the plus side, no losses for over 2 months. Kat Hentsch _________________________________________________________________ Windows 7: Simplify your PC. Learn more. http://www.microsoft.com/Windows/windows-7/default.aspx?ocid=PID24727::T:WLMTAGL:ON:WL:en-US:WWL_WIN_evergreen1:102009 _______________________________________________ GSAS-Member mailing list GSAS-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/gsas-member