Question about Lovan racks

I have the Sovereign series racks, but was a little confused on how to fill them as well. I had to knock out the caps on top of each stand. I used a threaded rod (bought from a hardware store) and a hammer. I also filled mine with lead shot (from a gun store), the welds weren't closed enough to hold sand. No ringing anymore.
In addition, I bought some sorbothane sheets and cut strips to place the shelves on instead on the rubber feet.
http://scientificsonline.com/Product.asp?pn=3037000&sid=google&cm_mmc=google-_-cpc-_-edmu-_-sorbothanesheets&bhcd2=1167063033

The holes are only for the crossbars. To fill the support columns, you need to unscrew the cone feet and fill thought the screw hole. The welding of the columns is not tight. Don’t use play sand or other fine grain as it will leak through the gaps.

If your goal is to reduce the ringing, I suggest you try isolation expansion foam. It is cheap, easy to apply, light weight, won’t leak, and very effective. Just inject the foam into the hole, wait for it to expand, and remove any excess that come out of the hole.

You can also try mixing sand or steel shots with the isolation foam to give the rack a little more weight. Just inject a small amount into the hole, than quickly fill it with sand or steel shots before the foam fully expanded, shake it viciously, and top it off with more foam.

Hope this help and have a great holiday.