Yes, you will need cured LR rubble. If you replace your exsisting bioballs with baserock you will see a pretty big ammonia spike. Just start going to LFS in your area and ask them if they have any LR rubble in their curring tanks that you can have.
Some people are like slinkies...they serve no real purpose yet can still bring a smile to your face when you push them down the stairs!:p
Have a great day! Brian