Can you look and see if you have copper plumbing, maybe where the water line or meter enters your home?
Another thing to try is to let your tap (faucet) run for 3-5 minutes and then use the water for water changes. Sometimes water setting in the pipes, especially newer copper ones, haven't built up the coating inside that normally reduces the amount of copper leaching.
Another thing to try is to let your tap (faucet) run for 3-5 minutes and then use the water for water changes. Sometimes water setting in the pipes, especially newer copper ones, haven't built up the coating inside that normally reduces the amount of copper leaching.