How much lead and silica sand in speaker stands?

What?!?!?! What are you looking at? Filled with pure lead, sure, you got a point. But then they would be so massive you need a forklift. So how ... wait, I know this is asking A LOT ... but how about some common sense? Two bags of sand, $4 a bag (if its even 2 bags needed) plus 5lbs lead shot per stand.

Like I said, what this world is coming to.....  

Oh and to answer the question directly- fill them all the way up. As much as you can pack in there.

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.

Alright.. I've gotten a good laugh at this one, mostly at myself.. Following my OCD instincts, I went to Bass Pro this afternoon and bought 2 - 25 lbs. bags of #4 lead shot and to the hardware store and bought a bag of silica sand. I filled them up, alternating between 2 cups of shot to 1 cup of silica sand. The stands ate all of the shot and most of the sand I bought. Yes you need a fork lift to move them around! If I can find my scales, I'll weigh them. I might have gotten carried away, but I don't imagine they'll be ringing.
Love the way the LS-50 Meta's are bolted to these KEF stands. 

https://en.wikipedia.org/wiki/Lead_poisoning#:~:text=Exposure%20at%20work%20is%20a%20common%20cause%....

Uh oh! Bolted, you say? Sorry. While that might be fine for keeping them on the stand, its not the way to go for sound. What you want is to make the stand as inert and stable as you can, and then allow the speaker to float above it. Nobsound springs are the easiest most cost effective choice. https://www.amazon.com/Nobsound-Aluminum-Speakers-Isolation-Amplifiers/dp/B07K9ZYP84 These things are adjustable - remove springs for lighter speakers - and its crazy how good they are for the money. They are now under virtually every component in my system.