.03 ppm copper on used rock

[ryewalk84]

I took a gamble on some used dry rock in hopes that it wouldn't have copper. It has been curing in freshwater since March 5th. The water has been changed a few times and the most recent 100% water change was done 1.5-2 weeks ago. The water is measuring .03 ppm copper on the high range Hanna Checker. I have also tested the fresh water before the rock went in it and that is showing 0.00 ppm. When I first got the rock it went through a bleach bath for the first week, sat in fresh water for another week, dried for 3 days and has been in freshwater since. Am I putting my tank at a substantial risk with .03 ppm? Should I get rid of it and order new rock? The rock is 200 lbs in about 20 gallons of water and will be going into an established reef of 270 gallons. Thanks in advance for the advice.

 

[35ppt]

If you soaked the rock in muriatic acid it would likely not be showing any copper now as it melts away the outer layer that would contain the copper. What you can do is either run polyfilter/cuprisorb/carbon to remove it from the water then keep testing the water and removing copper from the water until you get to zero or you could do a muriatic acid bath then soak the rock om water again to make sure you're rid of the copper.

 

[ryewalk84]

I went with bleach because it felt a little safer compared to the acid bath. Will have to read up on that some more. I probably should have soaked first and measured copper before doing the bleach cure.

 

[Randy Holmes-Farley Verified Community Expert]

It may be accurate, but folks have reported a host of what I think are spurious reading with the Hanna checker. One gut reported 0.06 ppm And 0.02 ppm by checker and only 1 ppb by icp.