I'm about to add water to my brand new 90 gallon tank. As I understand it, I'm looking at 6 weeks for a proper cycle. My question is this. If I set up a 20 gallon bare bottom qt with an hob filter does that need to cycle? There's no rock or substrate. I'd really like to add a fish to my qt and have it treated and ready to be added to the dt when the cycle is done.