Haha thanks for the tip. We deal with that issue alot where I work, it's amazing what certain chemicals (especially powders) will do to a sprayer. We've seen certain tanks even that get a build up of 1/16" of skin inside.
FYI, if you ever look into making a bigger sprayer, I'm designing a portable boom for aphid control/fertilizing/watering/sucker control etc. Can be used with any kind of sprayer set up, but wouldn't be useful for anybody with more than a hobby farmer
On comercial the best Aphid control is Admire . Add at transplant and you never see a aphid .One pint does three acres . They have the same type stuff for all bugs on garden vegetables to. Its for everything except corn .
I raise most of my tobacco for private sales and for myself as organic .