Kelly, have you used the granular Aquathol Super K?
Yes, but I sell far more Aquathol K (liquid) than Aquathol Super K (granular), mostly due to the economics associated with the liquid.
However, specific circumstances (besides convenience) may favor one formulation over the other.
Super K's polymer granule is simply a carrier (or "vehicle") for delivering its active-ingredient (endothall). Once applied, the granule releases its active-ingredient into the water-column within a matter of hours (transforming into "clear jelly-ice" in the process) and may remain visible for weeks or months after discharging its active-ingredient "payload".
Whether using the liquid or granular formulations, it is necessary to achieve and sustain a concentration of endothall within a target area that is deemed appropriate for a targeted weed-specie (as listed on the product's label).
