Cadmium and Aluminum?

[tmccaffery]

I am trying to figure out what will cause Cadmium and Aluminum in tank?

Last test showed on June 16th 2020 showed Cadmium 1.16 µg/l; Aluminum 4.60 µg/l

now on October 15th shows Cadmium 3.20 µg/l; Aluminum 1.59 µg/l

 

[Michael Hoaster]

I'm no chemist, but I believe GFO and/or other filtration media have aluminum in their ingredients. If you do run a medium with aluminum/cadmium, try taking it offline for awhile. Macro algae are effective at soaking up metals, so you might consider adding some to get those numbers down.