I swear by hard water. Then again, it depends on the type of hardness too. Most of the Midwest and Western US have liquid rock, that is tap water with very high CaCO3 content. In my opinion this is a good thing.
In some areas though, especially with well water, there can be extremely high iron and sulfur levels which are not good at all. If you have well water, run it through a good aquarium water test kit. If you have municipal water either look up online or request at the water office a copy of the annual tap water report.
It is really important what water treatment you use too. For instance, if your home is older and has copper pipes, you need to use a product that will remove these too. For most municipalities, chloramine is the sanitizer of choice. This can be problematic for some folks as they do not realize chloramine does not evaporate like regular chlorline AND it causes all sots of ammonia issues. (Chloramine gives a high positive result on ammonia tests.)
Not that I am plugging a product, but I swear by Amquel+. This is superior to regular Amquel and Prime in my opinion. If you can only get regular Amquel, use it in conjunction with Kordon's sister product Novaqua. Keep in mind though that Novaqua contains those "slime coat" enhancers which in my opinion cause all sorts of harmless but unattractive skin "issues" with aquatic smooth skinned caudates. Those enhancers may be great for fish, but my aquatics never did well with any of those enhancer products.
