graham products glow in the dark rocks 450pcs, glowing fish tank pebbles for indoor & outdoor garden/aquarium/plant pots/walkway/driveway, blue graham products glow in the dark rocks from graham products are an affordable way to add lovely luminous color to your home’s décor, both indoors and outdoors. these light-powered pebbles are perfect as fish tank accessories or aquarium gravel. add a few glowing stones to your potted plants to create a tiny indoor fairy garden. outside, the possibilities are endless. solar-powered glowing rocks make beautiful decorations for your patio, pool, night garden, landscaping pond or stepping stones pathway. made of plastic resin, these glow-pebbles are safe and non-toxic for humans and animals. they glow as a result of photoluminescence, so your children will get a valuable science lesson by interacting with the stones. the stones are recommended for kids ages 6 and up, as they measure 1” in diameter and may present a choking hazard for younger children. these radiant rocks glow best when fully charged, after at least 2 hours in the sun or bright indoor light. the brightest glow lasts for about 1.5 hours and then fades gently over time. the stones will continue to glow slightly for up to 12 hours.