Will low levels of salt in my tank kill my plants?

[guppy]

It depends on the plant.

 

[Cnidaria]

Salt will normally be found in fw tanks. even if none was added. Salt is a by product of a chemical reaction. When an acid and base mix you get water and A salt. Rotting material gives off acids. Your water's buffers have a base in them. Fish waste should also have salts in it.

True, but not all salts are made of sodium chloride, and it is the sodium that the fish's cells need for osmoregularity (bringing in water). A cell (whether fish or human) needs to spend one ATP (unit of cell energy) to bring one molcule of water into the cell. Since water forms a sphere of hydration around sodium ions (about 60-100 water molecules) the cell can spend one ATP to bring in one sodium ion, along with 60-100 water molecules, all for only one ATP.

Sorry, that was really nerdy.