|Is it true that salt kills plants?
It doesn't kill all plants. There's a huge study posted up (Look it up!) which itemizes exactly how different species of plants will respond to salt.
Salt can be used to eradicate a marvelous array of pathogens in Koi and Goldfish. However, there are some cautions to its use.
1. Plants, of the submerged variety, can be killed by salting. Iris, Papyrus (non Mexican), Hyacinth, Hardy Lilies, Water Celery, Cattails, Water Lettuce and Aurum will survive it - although they may yellow.
2. Salt should NOT contain YPS (Yellow Prussiate of Soda) or any trace minerals if using a feed salt.
3. Salt should not be used in extremely warm weather without GREAT aeration.
4. Salt will kill string algae - the decay of the string algae will pulse the Ammonia and also consume dissolved oxygen - AERATE!
5. Salt should be added, when possible, in a divided dose to negate any possible filter stumbles.