I would boil the HECK out of the rocks.
If any of the rocks look like they have shiny metallic bits in them, dont
add them in as they contain metals that are harmful to aquaria.
Slate should be fine in your tank, bu once again, boil it!

HTH
"Amber" wrote in message
...

Hello,

I want to add some attractive rocks and slate that I have found in my
garden and collected whilst on holiday to my tropical tank, however I'm
wary of introducing nasty's.

What is the correct procedure please?


--
Amber