I have a t5 nova extreme for a few years, has been working fine until yesterday, 2 bulbs can not fire, does that means the ballast is dead? Where is the good place to get a new one?
Are you comfortable opening the fixture up and finding out what brand ballast is in there? Or maybe a search will tell you what kind of ballast those fixtures run. In either case, you may be able to find one at a local hardware or Home Depot type store, if not online.
I once drove out to Long Island to pick up a replacement ballast in a pinch, you can search for the type of ballast you need and find a location nearest you who has them in stock.
in all seriousness what are aquarium lights? they are a product that was previously used for simething different than what we use them for and we just changed the application. open it up, take it out and take it to home depot, lowes or some other hardware store to get a new one. thats probably the cheapsest solution without replacing the unit and it would cost more if you went to a store because thats honestly what they would probably do to replace it