firebricks safe for fish?
 

can anyone advise if firebricks are safe for fish ponds? i made a
pond with a one foot deep plant shelf, but my plants need to be up a
little higher in the water. i put the flower pots on old firebricks i
had laying around the yard. i waws wondering if they are made of
anything that would leech out and harm the fish. Any thoughts on
this?

Tony