I think you have made a wise choice! I have an XP2 & an XP3 and love them! I have the bio stars in my XP2 and regular bio balls in the XP3. I really don't notice a difference. The bio balls might be cheaper for you. I also noticed that my foam would get so clogged after a month that I would have to replace them. I now bought extra ones and wash the clogged ones without detergent or chemicals in my washer and reuse them. Enjoy!
