After opening our pond the water has turned a dark stained tea color. What do I do??

The reason you have dark stained water is because organic matter has gotten into the pond usually from rain run off. You should try to correct this problem by making sure your liner is high enough that you do not get run off.
Treatment: You can purchase the Activated Carbon as a treatment for this problem. Place bag of carbon into the biological filter and leave in for 6 months.