I would try dropping the temperature down to just above freezing from 77F. The yeast cells should sediment if the temperature drops quickly enough and the culture is a Frohberg strain such as W-34/70 (Saaz-type strains may not settle due to their improved cold tolerance). The culture should be left at this temperature until you are ready to decant the supernatant (the clear liquid that lies above the solids). The supernatant should be decanted immediately upon removing the culture from the refrigerator; otherwise, the yeast cells will go back into suspension.
Most brewing yeast cultures are NewFlo flocculation strains (FLO is the name for the family of genes that control flocculation). NewFlo flocculation is inhibited by the presence mannose, glucose, maltose, sucrose, and maltotriose. Hence, most brewing strains will not remain sedimented until all of these sugars have been consumed or have reached a genetically encoded level.
All of the sugars encountered in brewing are multiples of CH2O (carbon hydrate or carbohydrate). Mannose and glucose are monosaccharides that belong to a family of sugars known as hexoses because they contain six carbon atoms. All of the hexoses have the same chemical formula; namely, C6H12O6.
Maltose and sucrose are disaccharides that consist of two hexoses bound by what is known as a glycosidic bond. We lose one water molecule for every glycosidic bond; hence, the chemical formula for maltose and sucrose is C12H22O11, not C12H24O12. Maltose consists of two glucose molecules bound by a glycosidic bond. Sucrose consists of one glucose molecule and one fructose molecule bound by a glycosidic bond.
Maltrotriose belongs to a class of sugars known as trisaccharides. Trisaccharides consist of three monosaccharide molecules bound by two glycosidic bonds. In the case of maltotriose, it is made up of three glucose molecules bound by two glycosidic bounds. The chemical formula for maltotriose is C18H32O16.
By the way, there are non-NewFlo brewing strains, but they are outnumbered by the NewFlo strains by a large margin. The non-NewFlo strains belong to the Flo1 family. These strains are inhibited by the presence of mannose. As Martin covered in his recent article, flocculation is dependent on calcium (Ca2+) ions. That’s because the substance on the surface of yeast cells that causes them to stick together is a lectin-like protein that is encoded to recognize sugars. Lectins require Ca2+ for binding activity.