How to introduce rocks into tank.

[YaYgoldFish]

I have these 2 rocks i got from outside that i wanted to put into my tank. How should i be sure i can put these in my tank safely?

they look like these but smaller..wayy smaller about fist sized.:

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[Rue]

Test them with vinegar...if they fizz...don't use them...

...otherwise you can scrub them and boil them...or scrub them and bleach them...

[zackish]

Test them with vinegar...if they fizz...don't use them...

...otherwise you can scrub them and boil them...or scrub them and bleach them...

Just out of curiousity...if the rocks fizz what does that mean?

[Chrona]

Just out of curiousity...if the rocks fizz what does that mean?

Contains carbonates which will raise kH/pH

Use muriatic acid instead. Vinegar is a really weak acid and it's tough to tell in borderline cases. Wash it thoroughly afterwards of course. Muriatic acid is sold with pool supplies and is also used to clean concrete.