BioDieselNow - Renewable biodiesel fuel

Seems to me just about everyone is using a pump (recirculation) as a method of mixing (Agitation)
Is this due to cost? Or is there some science that I have missed?
I like to use a mechanical approach; like a paint stirrer on a drill, only larger.

Also, Meth oxide is almost always introduced into the reaction from the top? Is that also economics, or “just the way we do it” thinking? Is there any reason why the Meth oxide isn’t be pumped in from the bottom?

Just a couple design thoughts and I’d sure like to get some practical opinions

 I use an agitator for mixing in all of my tanks.I find that an agitator works extrem ally well  for me. With an agitator type system you know you are getting a good mix because everything in the tank will be stirred together. That being said,mixing with an agitator is more expensive because of the added cost of a gearmotor systen on each tank.But I have had fantastic success with this type of system. Mixing with pumps however does work very well too. As long as the pump is designed for this type of applicafion.  Hope this answers your questions..Duff Streeter  www.michiganbiofuel.com

Found a Company in my neck of the woods that has 30 acres of used Food & Chemical processing equipment from Dairy, Chemical Manufacturing, you name it!
A Biodiesel-Processing paradise; they are not giving the stuff away, but for a few thousand I’ll have a nice set-up;
300gal. Jacketed/Insulated Stainless Steel Reactor w/x-proof motor/Mixer,
60 gal. Stainless Cone Bottom Methoxide Tank
a dandy 4,500gal. 5-Compartment WVO De-Watering/Pre-Heating Tank formerly used for skimming oil. 
6,500gal. Horizontal (several actually) that is fully insulated and has a built-in heater…