How much lead and silica sand in speaker stands?

Do not use either, lead is toxic and sand will make a mess and can seep out. Go to your home improvement store and by a bag of small pebbles and use them, they are stable, safe, easy to handle. Shake the stands after filling at different levels to make sure they are tightly packed. If you have to empty to sell or ship, just pour into a 5 gallon bucket. Make sure they are dry before filling.

Lead shot now is expensive. I looked at the OP's system and if he is using the stands in the the photo, he needs quite a bit and sand can leak, over time, especially if you move them around. Been there, done both. I have found that small pebbles or pea gravel works very well with no need for sand and much cheaper. Very solid, no ringing and won't be a lead, sand, mineral oil mess if they need to be emptied for moving or to sell.

So why go to trouble of getting lead & sand, when pebbles or pea gravel will work just as well? Plus, it is much easier to deal with if a move is needed. 

" Like I said, what this world is coming to.....  "
Imagine that, someone else's view that is not yours. Deal with it.