Thanks for the comments!
Paul in Ireland- Like I said, maybe it was just bad luck and the knots weren´t bleached. And yes I´m gonna try the I-Lace 'Island' and I think there´s not going to be any problems. But like Xeon005 says, I also think that pieces with more density have bigger knots because they have multiple hairs coming from the same knot. I just have to decide about the density, if I order a 10% less than the last time (last time was 70%)
Thanks to all!