I siphon.
In general if you try to siphon it right off the sand you will surely pick up some of the sand but you will get most of the
detritus. If you blow it off the sand and into the water column you will not pick up sand but you will not get as much of it.
Now for the questions... I am concerned that it sounds like you are seeing a significant
detritus buildup. How deep is the sandbed? How much flow is in the tank? How are you filtering it? How much
LR do you have in the tank? What kind of fish do you have and how long are they? Also if you are seeing
detritus buildup in the tank you may also have it in the
sump compartments and this would need to be siphoned too.
