Would it be harmful if i were to use crushed coral or washed beach sand for gravel in my tank? I want my tank to have pure, natural gravel in it and I would obviously wash it thouroughy before i put it in.
Originally posted by RTR
daveedka is leading you in the right direction. Part of your answer will depend on what you are planning to keep in the FW tank. I use "marine" substrates (crushed coral, aragonite, etc.) in FW for fish such as Rift Lake and certain Central American Cichlids which come from hard alkaline water, I also use such in low-level to very low-level brackish water where the low level additions needed for low specific gravity might not quite do the job again on pH support I would like.
For routine FW tanks I would not use these substrates as they will chronically increase the hardness and pH of the aquarium water. There you will want inert substrates which will not affect the water chemistry.
HTH