How To Know If A Stone/slate Is Safe To Use

[alimack71]

hi there am needing a wee bit of advice am looking to make myself a cave/hidy hole for my loaches/catfish i work for a builder and there is a lot of welsh slate(blue slate)lying about that i was going to cut to my requred size and silicone together with aquarium silicone i however dont want to put something in my tank thats going to be harmfull to the fish
my friend tells me that i should be able to know if it is ok by pouring vinegar over it and if it reacts then i cant use it is there any truth in this or is he winding me up any help and advice would be gratefully accepted

 

[rdd1952]

If it's small enough, you can boil it to kill any bacteria that may be on it. Other than that, a good scrub with a solution of 1 part bleach to 20 parts water will probably work too. And your friend is right about the vinegar. If it fizzes when you put a drop or two of vinegar on it, it is lime based and will cause your pH to rise. Not generally what you want unless you are keeping African cichlids or other fish that prefer a high pH.

 

[OldMan47]

The idea of using a weak acid like vinegar is a decent first screening for a stone. In my own experience it ends up not being sensitive enough. It will save you getting too frustrated so when I have a stone that seems to be OK using that test, I put it in a bucket of tap water and fill another empty bucket with water. After a day or two, I measure pH in both buckets. If they are still matched, I feel the stone is not going to affect my pH enough to worry about. If the pH of the bucket with the stone in it is at a higher pH than the water sample, I figure the stone will raise my pH. At that point I need ot decide whether or not I am willing to have a stone in my tank that is raising the pH. If not, that stone gets set aside and I work with something else.