Copper Levels

[jgsensor]

Just tested for copper in my tank and it tested .05mg/l. Not sure where this came from, I have never dosed copper in the tank ever. Would this low level have an effect on anything? I have been having trouble keeping corals alive for sometime due to phosphates. Finally got those down using a reactor and phosphate buster, but still having trouble with the corals and coraline algea. I have had no trouble with keeping snails, crabs, starfish, and fish alive just the corals.

All other levels tested good at last check, but I am going to retest them tonight. At last check they were:
Salinity 1.025
PH 8.02
Calc 450
Alk 9.3
Mag 1350
temp 79.2
amon, nitrite, nitrate 0,0,0