Removing unreacted Mg metal in a Grignard reaction

We had what we would call "filtersticks", they were a cannula with a metal cylinder with a bore at one end, around which we would tie glass filter paper. Larger quantities we transfer through polyethylene tubing to a filtration column and filter through a pad of Celite. Both methods worked well.

Since your product doesn't sound air-sensitive, you might consider quenching with wet THF. Have an ice bath and a fire extinguisher ready.

Pure water would certainly be a bad idea, but a 1% solution of 1 M hydrochloric acid in ether would probably work without a vigorous reaction.