A modular poppet assembly system for a toilet tank flush valve assembly, the modular system comprising a first float portion; and two or more second float portions; wherein, the first float portion is configured to removably attach to each of the two or more second float portions to form two or more poppet assemblies, each of the two or more poppet assemblies comprise a different buoyancy, each of the two or more poppet assemblies allow the toilet tank to fill to substantially a same water volume, and as the poppet assembly buoyancy increases, an increase in flush volume is provided.