Can I Use These?

[white9870]

i want to add sum rocks into my new aquarium, can you use rock from the garden? and can you use any from an outside pond? would they be safe to use if i let them soak in boiling hot water. thanks

 

[Josh!]

I think to test whether they're suitable for an aquarium or not, you pour a bit of vinegar on the bit of rock you want to use, if it fizzes then it's not suitable to use.
If it is suitable to use then I'd also say giving them a good clean is a good idea, probably with boiling water like you said.

 

[fluttermoth]

Vinegar isn't really a strong enough acid to fizz on unsuitable rocks; rust remover will though. Or you can stand two containers of water for a week or so; one with plain water and one with your rock in. Then test the pH and/or hardness of the water and see if the one with the rock is higher than the plain water.

If they have been in a pond then pouring boiling water over them and then letting them dry completely is sensible precaution; do not, under any circumstances actually boil the rocks; if there are air pockets inside the rocks, they could explode

 

[Josh!]

Ah, thanks for that - I didn't realise it wasn't strong enough.