Why does my horchata have too much sediment? I've tried a few times to make horchata.

My process is as follows:


Put 1 cup of long grain rice, one cinnamon stick, and 4 cups of water in the blender.  
Blend briefly to break up.  
Let soak for 3+ hours.  
Blend thoroughly.
Strain through a fine mesh strainer.  
Sweeten and chill.


The flavor is fantastic but there is a large quantity of rice sediment and the texture overall is gritty.

This sediment is fine enough to pass through my muslin so I don't think more straining will help much.

What do I need to do to improve the texture of my horchata?
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.