Hi, we got this paddling pool the other day: Summer Escapes 9ft Octagonal Family Paddling Pool - 1806L and started using yesterday. Left water overnight and using again today. Is it safe to use same water overnight? How long can I leave the water? Should I change it every day? Or is there something I can put in the pool to keep the water safe for the children? Online searches talk about chlorine and pumps! But not sure if this is pertinent to the pool we have. Thank you