How to test for copper in my water?

[Sublimer]

Hi all. I've been cycling my tank for what seems like a month now and before I get my crabs this week I wanted to make sure there was nothing in the water that could harm them. I've added salt to make the water low end brackish for acclimation purposes, I've dosed the it with calcium, and the ph level is where it should be. But I've heard that copper traces are harmful to inverts and I was wondering whether there was a foolproof way of testing for it

 

[armymp327]

API makes a copper test kit

Copper Test Kit - API

 

[Berylla]

Your question spurred me to do some research on the Internet. Apparently, copper is difficult to remove from water. An RO system will remove 98%. To completely remove copper from a tank (say after using a copper ich treatment), you need to do massive water changes over a couple of days. Carbon will remove a little of the copper, but not to safe levels for snails and invertebrates.

If you have copper in your water and you suspect that it's killing your inverts you may have to install an RO system.

Anyone who has high copper in their water supply, please chime in.