[Delphinus]

I totally went into this thinking I would do the rod thing as well .. I went as far as buying acrylic rods. In the end I just don't want to bother drilling the rocks. I have a hard enough time getting rocks to fit together "just so" anyhow, so I figure I'm further ahead to just do it once and then cement the pieces together rather than try to find the right angle to drill and then wiggle the rock onto the rod and etc. etc.

I did find a different product - forget the name now but I can check it later and post back if it works out - like Thorite it is a "polymer based patching compound" so theoretically it should also be tank safe. However I'm going to test it first, I'll put a bunch together and let it sit in water overnight and see if the pH changes at all.

Then again, some people just use regular old cement .. Since it's a small amount comparitively the pH spike might be minimal and since the tank sits empty anyhow at first to cycle maybe it's a non issue..