On my first brew the krausen fell and all of the stuff floating on top fell to the bottom after about 4 days. My current brew has been going 6 days and there is still some stuff floating on top. It's not a whole lot just a very light layer. In some places it kinda looks like dust floating on top. Some places it looks more foamy. Is this ok? I am planning to rack tomorrow if the gravity stays steady. Should I wait for this stuff to sink to the bottom?