sand versus shot in speaker stands

Lead is preferable for weighting speakers IMHO. Handle it gently; just don't put it in your mouth or nose and you won't die or lose your mind.

Given the possible toxicity, I put it in ziploc bags first - the in the speaker base.

When I have used it, I wore nitrile gloves and a basic painter's mask. Just handle the lead gently and if possible, don't pour it from one container to another as this might create dust.

Remember - don't eat, breathe or otherwise ingest it.

Here's a link: http://www.rotometals.com/Lead-Shot-s/64.htm
You want 8.5 or 9...

I am using graphite coated lead shot ,which is very good and the graphite absorbs added vibration. On Amazon 25lb bags $50 free shipping 
And yes you can go to home depot and get some plumbers puddy to seal the top.then put your top plate on .

Manufacturers have long supplied tin-coated lead shot to eliminate even the possibility of lead dust and associated hazards. Once mixed with sand (recommended) and sealed inside the post of a speaker stand, no more dangerous than sand alone.