Lowell - the Hypro folks are right. Roller-pumps are best suited to non-corrosive liquids (no wettable powders or abrasive products).
Diaphram or piston pumps (12v or gas-powered) are much more versitile in respect to what they'll handle, though a bit more complicated to plumb.
Here's a commercial-grade 12v sprayer that I assemble for lake management companies (twin 12v 3.6 gpm pumps with individual or consolidated output, plus agitation for a 50 gal mix-tank).
It is definitely more capable than what most private pond-owners need. But, if you purchase a 12v sprayer, be sure to look for a pump with at least a 3 gpm capacity (suggestion). It will provide much greater reach and mat-penetration capabilities in comparison to the little 1.4 or 1.8 gpm pumps.