A bit of reading on the subject of corrosion in electrical panels & the primary causes. Seems we need to be aware of more than a fish tank or bathtub in the basement. I guess no matter what your set up, it's a good idea to have a peek inside the panel from time to time, or have an inspector do it if you're uncomfortable taking the panel cover off yourself. Perhaps make it at least an annual routine, like replacing the battery in your smoke/CO2 detector.
http://inspectapedia.com/electric/HolmConf.htm
http://inspectapedia.com/electric/El...l_Moisture.htm
http://blog.schneider-electric.com/p...ensation-away/