Container, cartridge, kit and method for slow release of algaecide in swimming pools

A method for adding algaecide to a swimming pool, comprising:

• providing the disposable prefilled cartridge of 23;
• dropping said disposable prefilled cartridge into the pool,
• wherein the prefilled cartridge sinks to the bottom of the pool when filled and floats at the surface of the pool when empty;
• recovering said cartridge at the surface of the pool when empty;
• and
• discarding the empty cartridge.

A disposable prefilled frustoconically shaped cartridge (1) for the gradual release of an algaecide into a swimming pool, comprising:

• a single piece, frustoconically shaped, plastic housing (10) with a frustoconically shaped sidewall defining an interior volume, and having:
• a top portion (12) having a central hollow bump (13) extending away from the interior volume and having an annular void (15) defined between an uppermost portion of the frustoconically shaped sidewall defining a rim (17) and the central hollow bump (13), an interior portion of the central hollow bump (13) defining a sub-hollow space (14) open to the interior volume;
• and
• an open closeable bottom portion (11) disposed at the bottom of the frustoconically shaped sidewall;
• a lid (40) for covering the open closeable bottom portion (11) of the housing (10), wherein said lid (40) is detachably connected to the open closeable bottom portion (11) of the housing (10), or comprises at least one opening extending therethrough, for allowing a flow of liquid into the interior volume;
• a water-soluble water-treatment tablet (20) disposed within the sub-hollow space (14);
• and
• a water-soluble algaecide material (30) that is compositionally different from the water-soluble water treatment tablet (20) disposed within the interior volume, covering and surrounding the water-soluble water-treatment tablet (20) and the sub-hollow space (14).