Just wondering if you are in the northern or southern hemisphere?
I noticed that you are rotating your vortex CCW. If you are in the northern hemisphere you are losing energy to the coriolus effect (or force if you prefer), albeit a small amount. In the pursuit of ultimate flow which I gather you are after, and if you do use a whirlpool mixer resevoir, spin CW in the northern hemisphere and CCW in the southern for the most OOMMMFFF!!
