BigB
Well-Known Member
A friend of mine has a salt water aquarium. When he compensates for evaporation, he adds water from a small reverse osmosis filtration system that appears to be of the type that is typically mounted under a sink. He claims that he could not use that water for brewing (even though it is not attached to the aquarium, he just uses it to add water to the aquarium). This sounds fishy to me (pardon the pun). Is there really any difference???