I've been spraying for about 4-5 years and building up a good app side to my business. As my clients grow I am trying to decide to go with more capacity or lower flow in order to be more efficient. Right now I use prodiamine as my pre at .5 gallons per 1000 and when i do weed control i increase my speed so I can go a little further. Rates depend on who you ask and some hose guys say they won't go less that 1 gal/1000 and some boom guys say they go as low as .25 gallon/1000. What is your flow rate on pre and/or post? I asked Ray at z-spray about more capacity and it turns out they have a second 18 gallon tank that is interchangable with the hopper on my jr.