There's a method called read_queryset on the SearchIndex API. I just had to override this:
class AnuncioSolucaoIndex(RealTimeSearchIndex):
text = CharField(document=True,use_template=True)
def read_queryset(self):
super(AnuncioSolucaoIndex,self).read_queryset()
return AnuncioSolucao.objects.filter(is_active=True)