Why does my horchata have too much sediment?
One technique which seems to be effective at straining out fine sediment is gel clarification with gelatin or agar. Dave Arnold's research on agar clarification culminated in an approach which uses agar, an ice bath, a whisk, a cheesecloth or muslin, and about an hour.


Measure out 0.2% agar by weight (as a fraction of your total liquid quantity).
Whisk it into 1/3 of the liquid to disperse, then bring to a simmer while stirring and hold it there until the agar is hydrated.
Pour in the rest of the liquid slowly while whisking, keeping the temperature about 35C.
Leave to set in ice bath.
Gently break up the gel with the whisk and then sieve through the cheesecloth.


The gel will trap the sediment, but leak liquid.