I've been doing this a while now and have probly cycled 20 tanks. I'm also a biologist. I think they must either put cycled sand in the sump, which they never really show, or use some type of fuge. I have noticed in cycling my tanks that cycles are always different and in truth a rank actually has many cycles not just 1 bug one. For the poster above who is 4 days in without a cycle, it is coming my friend, it is inevitable. Just hope it's multiple small cycles not 1 big.