I am going to post a question here, although I hope no one sees this as a hijack and gets offended. If so, feel free to split.
So, when I started keeping reef tanks again after a 10+ year hiatus, I brought some of my old school techniques with me. 4 months later I have a successful tank, thanks mainly to this site and my local fish club. However, if I could change any one thing, it would be the coarse crushed coral substrate I used when I put together this tank.
I read all the time about aquarists switching out their deep sand bed because of accumulation of heavy metals (e.g. copper) and I don't quite understand how they do this without messing with the water quality of the tank. I also don't know if this must be done by removing everything first, replacing the sand, and then replacing everything - or by doing a section at a time, taking out as much as possible and the just covering up the old stuff.
I would LOVE LOVE LOVE to replace my crushed coral with a 2-3 inch sand bed. I currently have about 55 lbs of live rock with fish, inverts, zoos and LPS.
I had considered getting some aragonite, doing a water change... taking the old water and soaking the new sand in that, then taking the old substrate out a little at a time.
I'd love to hear thoughts about this.