Brightwell neomarine salt, redsea sand no fake decor no pvc. Tonga branch for scaping. In the sump I put macro algae, a marine pure block to supplement the minimal scaping the skimmer and then filter floss with polyfilter and continuum heavy metal reducer. Carbon in a reactor then the return pumps.
There's been a lot of speculation that the marine pure blocks contain and release a lot of aluminum so I think that's where that is coming from.
In regards to Cu, are you using LR that was fresh from shipping, etc or did you buy used LR? If used, previous owners could have treated their tanks with Cu...
I was told the Cu could be due to Triton not backwashing their system, do you think there is any truth to this?
My LR was new and I soaked it for about two months in RO before putting in the tank. I might pull the marinepure out and do water changes and rerun the test to see if the aluminum drops out.