Thanks for the article, today I made 10% water change and added Seachem Prime, which according to the instruction removes heavy metals. Also, I noticed that my PO4 levels are at 0,05-0,1 ppm, is it a concern for BROs ?Most of this sounds great, but copper is a huge no-no when it comes to cephalopods. They have copper in their blood and use it to bind oxygen to their bloodstream. Any trace amounts of copper in your system can and will kill your animals. I would recommend adding a copper absorption media asap to keep your animals safe. I can provide a link to what I use if you'd like.
Copper... Is it really that deadly?
Here is a link to another TONMO conversation about copper in ceph-tanks. One of our moderators shared some insight they have from 10 years of experience. Copper is bad.
Nitrate was 10ppm before water change.