First homemade stir plate in a cigar box. Cost: $5 (the 1" stir bar). Computer PSU fan with hard drive magnet. Powered by another computer PSU converted to a benchtop PSU. Current output voltage to fan is 7V (10V is too fast; the stir bar spins off). Does this look like enough vortex for a 2L sample (in a 1gal. jug)?