the thread I linked before is a super good read, he already did what I am doing. I will say chemically speaking it absorbing into the silicone seams is definitely implausible, but given how porous the rocks and sand are it will probably sequester some.Good to see someone documenting this! I hear the same thing with freshwater shrimp (if you've ever used copper you can never add them to the tank) and it always seemed a little implausible to me - if a finite amount is added, then even if some copper is taken into rocks/sand/silicone seams and leaches back out over time, the amount present must decrease. It's just a matter of how long it takes for the level to reach an acceptable value.