I had the same issue, but I did not have any rock. Like 2cents, I threw out my substrate, as this is the main concern for unwanted copper after treatments. I soaked my tank a day in a bleach/water mixture, then soaked it in tap water with a dechlorinator and the allowed it to air dry for 2-3 days. Did copper test and none was testable. I do not think it was the bleach that got rid of the copper, so that suggests that none or miniscule amounts of copper were in the seals.
For the rock, I would put it through the curing process again in a bucket or two and test it with a good copper kit. If so ditch the rock too. I'm no expert, but I'd imagine that the copper could find it's way into the deep cracks of the rock and you'll have to start with new LR
. Rock and substrate have very similar properties. Sand in the ocean is just weathered down rock through ages and ages of colliding and grinding due to tides and waves. So my guess is, if you gotta ditch the substrate, adios to the rock as well!