When cleaning glass beads, it's not sufficient to simply sterilize of cells, but also destroy all DNA, and perhaps even labile organic molecules such as antibiotics, proteins, cofactors, quorum signals — molecules that could interfere with sensitive experiments. Many researchers use ethanol like a panacea, but DNA is insoluble in ethanol (hence it being the main component in DNA purification wash buffers). Ethanol is fine for preventing microbial growth on used beads and drying of residue on them, which otherwise makes cleaning more difficult.
For routine cleaning, you need to destroy organic molecules. Some protocols use an HCl solution, but it's been found that even a strong acid-wash is inferior to simple bleach in destroying DNA¹ ². A good protocol may look as below.
Dilutions of bleach (commonly 10%) ought to be used within a week or two to maintain enough hypochlorite to be effective, so make only squirt-bottle quantity dilutions. Use deionized water in dilutions, as metals in hard water accelerate hypochlorite decomposition, and store in an opaque container or dark cabinet if possible, as hypochlorite is photolabile.
¹ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4943653/
² https://www.ncbi.nlm.nih.gov/pubmed/1571142