a solid chemical feed unit dissolver has an upper feed unit chamber with an inwardly tapering sealing surface at its lower end and against which a lowermost feed unit seals , retaining the upper chamber in a dry condition , preventing wetting and caking of solid chemical feed units behind the dissolving and sealed off face of the solid chemical feed unit . a solid chemical feed unit magazine is slotted to permit gentle feeding of a plurality of solid chemical feed units therein and a cover - defined sight slot permits guiding and visual observation of remaining solid chemical feed units in the magazine . the magazine preferably , but not necessarily , defines the tapering sealing surface . distinctly shaped solid chemical feed units are disclosed . the dissolver can handle large solid chemical feed unit loads up to one hundred pounds or more and in a small footprint stable configuration . methods are disclosed .