hi all, is coral sand good for guppies as substrate for a 7 gallon tank? thanks!
The addition of NaCl at the same 1 tablespoon per 5 gallons as beneficial for livebearers. Here the pendulum swings closest to agreement with the myth. These fish as a group are native to estuarine environments where the waters are likely to be hard and alkaline at least, and may be brackish. Sodium chloride is matching their home, right? Well, maybe. If your water is moderately hard to hard (GH 8-12 or more, KH the same range), then some NaCl addition may be all that is needed, if anything is needed at all. If your water is soft and acid, you need buffering and increased TDS as much or than the addition of specific minerals to the water, and NaCl alone will not be sufficient. You need to add crushed coral or aragonite, perhaps plus salt, or just the use of marine mix rather than table salt alone.
under urban legend 3E: http://www.theaquariumwiki.com/The_Salt_of_the_Earth