Rocks from a terrestrial environment I just give a good scrub to. I can't imagine what could be on them that would act as a pathogen in an aquatic environment.
Rocks from a stream I would sterilise in some way. You can get very good sterilisers, chlorine or sodium metabisulphite based, from home brewing and winemaking shops. The latter is toxic to higher life forms only in larger amounts; you even add the stuff to wine to sterilise it in the form of tablets. I would suggest that sodium metabisulphite and citric acid (warning - don't breathe in the fumes unless you need a really good cough) would make a good steriliser for rocks and gravel. Easily rinses off.
Wood I buy from the LFS. I've never had problems with LFS bogwood floating, or indeed any other problems with it. I quite like the colour and believe that the tannic acid is good for the plants and the sort of fish I keep in tanks containing bogwood.
Rocks from a stream I would sterilise in some way. You can get very good sterilisers, chlorine or sodium metabisulphite based, from home brewing and winemaking shops. The latter is toxic to higher life forms only in larger amounts; you even add the stuff to wine to sterilise it in the form of tablets. I would suggest that sodium metabisulphite and citric acid (warning - don't breathe in the fumes unless you need a really good cough) would make a good steriliser for rocks and gravel. Easily rinses off.
Wood I buy from the LFS. I've never had problems with LFS bogwood floating, or indeed any other problems with it. I quite like the colour and believe that the tannic acid is good for the plants and the sort of fish I keep in tanks containing bogwood.
