Shouldn't need any filters at all. If you're looking at full tank shots, the kit lens may work out okay, but won't be the best.
There are 2 lenses I'd suggest you get, one is inexpensive and a spectacular lens.
Canon 50mm 1.8 Prime. "Prime" means this is not a variable zoom lens. It's stuck at 50mm. It's an amazing lens and can be purchased, new, for around $100.00. It's nicknamed the "Nifty Fifty."
Okay, now on to the expensive lens, but a great lens for those beautiful Macro shots you wanna take.
Canon 100mm 1.8 Macro
This lens is an amazing piece of glass. It'll take wonderful Macro shots, but is also great for portraiture photography. It'll also take incredible full tank shots, as long as you can get far enough from your tank.
For an all around lens, I'd recommend Canon 18-200mm. This lens isn't as "fast," but will work out really well for a wide variety of photography needs, including tank shots, as long as you get enough light.
We also have a Photography Forum, here on Reef Frontiers.
http://www.reeffrontiers.com/forums/f6/