My sand-filled Bright Star Audio bases have been exposed to air for 6 years now with no problems. I'm certain because I just emptied them the other day and the sand flowed freely. No damage to the frames was observed either.
I found my meds !!
Revel Ultima Salons & Voice / PSB B5 / PSA XV-15 / Emotiva XMC-1 / Emotiva XPA-5 / Oppo BDP-95 / Sony PS3 / Cable-TV / Panasonic 50" Plasma / Samsung 60" Plasma
Custom McCormack Monoblocks / Custom Cary SLP98P / VPI Super Scoutmaster with JMW9 and Benz Micro Glider H2 / PS Audio PWT / PS Audio PWD with Network Bridge