Adding large rocks

[Dennis The Mennis]

I plan on adding a large piece of Kyanite to my new tank. It is still a little dirty with native clay and iron residue from Brazil. I plan on cleaning it up as much as posible. However, I do not think I will be able to get everything. Will this have a negitive impact on the water quality or the fish in general? I also plan on adding a few other cryatals and rocks. Is there anything I should stay away from?

[chompy]

If your puting that in with discus I would have to say it's a bad idea. Your discus will get a serious injury from that rock. My discus have gouged themselves badly in a bare bottom tank with just a heater, thinking about the putting that rock in a discus tank makes me shudder :D.

[FishLover888]

Some rocks (if not most of them) will change your water PH. You may want to do a test befoer put it in your tank.

[Apistomaster]

I have to agree with Tyler. Discus manage to get scraped up plenty on heaters and such. This is inevitable with discus.
I have switched over to smooth weathered pieces of wood instead of rocks. Petrified wood is often available that isn't too hazardous to use but do avoid ragged edges, large pieces of quartz crystals or similar rocks. They may be chemically safe but mechanically jagged. I know how tempting these things are. I love it when I can use a very large piece of quartz crystal I have in an aquascape but I only do so with fish that are too sensible to crash into it.

[Harriett]

I agree with Larry and Chompy on that [admittedly beautiful but dangerous] chunk o rock. On the other topic about the composition being possibly problematic: to determine if a rock is going to prove alkaline and harden your water, one approach is to put the rock in a bucket and add white vinegar. If it fizzes/bubbles up, the rock is not inert--ok for African cichlids that like hard water but the wrong approach for discus.
Best regards
HArriett

[architect1]

I also agree, i have a piece of driftwood that scratches my discus when they get scared and I had to ground cutting the edges that might not of been nicely curved. Also I got some rocks from the beach and I think I got a algae problems from them, even after bleaching and boiling them. SO i took them out.