My audio rack is bright, will sand fill help?

Just a thought but whenever arranging or re-arranging components physically, particularly low level phono gear, be alert to any potential RFI or EM noise issues that could be introduced by something as simple as a power wire in a different location. Distance between components and from surrounding wires transformers, etc. can all make audible differences. It took a lot for me to get a handle on this. Adding mu metal foil shielding around my step up transformer was required to get things sounding best. The physical nature of the table or rack itself may have little to do with it as long as it provides a very stable platform. Keeping things low to the floor helps. Having a turntable sit way up high is often a mistake and putting that firm foundation in place much harder.

Adding weight/mass to the platform can usually only help and not hurt.

Whatever the case, good luck in solving whatever problem might exist.

As you no doubt know, many turntables are greatly affected by the surface they're coupled to. I'd suggest you try situating your turntable on an isolated plinth that sounds good and then you'll take the sound of the rack shelf out of equation (more or less.) Personally, I like the sound of the 3.5" thick maple plinth I've had under my previous VPI turntable and the current Acoustic Reference I have. The heavy maple plinth sounds better than any rack surface I've tried.

I would suggest a new rack. I had that vpi for a couple years and my analog performance went up dramatically when I ditched that rack for a mapleshade type design with 3" maple

Filling the tubes with sand may not be a complete answer but it certainly can help.

I think you mean VTI audio rack. As far as I know, VPI doesn't make racks other than the one the TNT came on.