We brush his tail EVERY day so it is completely smooth and tangle free. The next day we get there? It's completely tangled and impossible to brush. By the time I'm done brushing I've torn out a lot of tail hairs, like a handful..
We spray a LOT of detangler into it before we brush it, at least a half an hour before we do, we work it in and let it sit for a while. It doesn't help at all.
He always gets compliments on how beautiful and flow-y his tail is, but soon he won't have a tail at all.