I have been running my latest starter for about two weeks - a mixture of white and wholemeal flour. It is fully active. Using Peter Reinhart's recipie, I used some of it to build a firm starter over two days - that remained fairly active as well but I refrigerated it for the second night. Although the loaves from this firm starter rose quite well and crusted well, they lack a bit of spourdough zing. I am not necessarily a really sour flavour person but would like to have a bit more depth to the flavour.