Sand or Lead shot

Don't use either. You don't want to absorb resonance, but transfer them to the floor. I agree with all the guys who recommended Starsound's Micro-Bearnings. The difference is amazing. Call Robert over there and he'll give you the sonic scoop to what is actually (scientifically) going on. You'll be amazed. They are on to some really cutting edge things over there. I'm not a salesman. Just a very happy customer. Good luck.

Warrenh,

I've no doubt that you are pleased with Starsound's "micro-bearing" fill but the claims made for its functional properties as something other than a damping/mass sink mechanism is complete bollocks.
A number of the conceptual theories touted in their promotions simply undermines the credibility of an otherwise well considered and effective resonance control product line.

Micro-bearing steel was chosen for the specific application of transfering resonant energy to ground. Again Sistrum was designed as a high speed transfer agent not as a slow speed blurred focus, time signature distorted ,dynamic dampening device. My advice is to try these specific devices in your own system. I have been using them for almost 3 years now and have decided this science works and will not be replaced.

Tiny amounts of lead paint dust tracked into your home from shoe soles can cause severe health problems to children.