[Phil Edwards]

It sounds like your tank is cycling. Since you took out the material that was absorbing ammonia and whatnot that's the most likely source for a whitish haze. If it starts to turn green at all you've got a Green Water algae bloom and can use a diatom, UV, or Micron filter to clear it up. Alternately, you can just let it run its course.

Is your tank heavily planted? Are you using more than typical aquarium lighting? Are you using CO2?

Best,
Phil