Watch municipal water chlorine levels in spring
My local water company advised people with aquaria and on kidney dialysis (!) to use "extra precautions" when using municipal water for the next month or so. Apparently, it's common practice in water systems to superchlorinate annually (usually in springtime) as a means of disinfecting all the miles of water supply pipes. I don't know if it's unique to reservoir-fed systems with surface water like mine or all water systems. Though folks might want to be aware..