I used to be dead against biopellets because I saw so many people having troubles with them.  There are a few things to keep in mind when using them, and other than that they do their job - really well.  I don't need biopellets in my own tank, but I do use Prodibio (for good bacteria balance) and vinegar (to make the kalk more concentrated).  Though the latter two the carbon dosing effect is the secondary effect for me.  
