Is there a really good way to add wettable powders to a spray tank? 

 One of our sprayers has a small inductor so I premix the powder in a pail with a cordless drill and mixing rod and dump it into the inductor, but it can take quite a few mixed pails to top up the sprayer.  Sometimes the powder comes in slow dissolving plastic bags, which tend to gum things up at times.  Also, the inductor tends to foam things up very quickly in the tank if I have to use it a lot, and even anti-foaming agent doesn't get rid of all of the foam.  Seems to me that a good system would be a BIG inductor with some way to swirl and dissolve everything before ejecting it into the tank.  Is there such a beast, or does everybody just stir with a mixing rod and get dust all over themselves?  Can the larger inductors take large loads of powder, suck it, and mix it while they're injecting it into the tank with no clogging or foaming problems?  I'm getting tired of ending up with white clothes when spraying powders, and there's gotta be a faster way to do it.  30 mins to an hour to tank up doesn't seem reasonable.