Amber wrote:

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?

The main danger I've found in this is what various rocks do to the Ph. I would
place the rocks in a aerated container of water for six weeks or so and test the
water. You may wish to dunk them in a chlorine bleach bath before that, just to
kill off any nasties that might be hanging on.

George Patterson
I prefer Heaven for climate but Hell for company.