Question
Our pond is 12 X 20 X 3. We have about 17 fish mostly Koi but we do have goldfish also. We had alot of flashing so we went to our Koi people and we put in something called Terminate, and thats what it did. It killed all the algae and the biological filter was gone now also. We worked very hard at fixing all of this and we thought we had it fixed and now the fish are flashing again and one of the biggest has a lifted scale and an ulser around it. I am so frustrated what do I do now.

Answer
Hello Pat!
Flashing is usually associated with some sort of parasite. First of all, the water quality needs to be checked. Make sure levels for Ammonia and Nitrite are 0 (zero).
Bringing the biological filter back into action is of utmost importance!! Do not feed the fish until that is accomplished. They will be fine for up to 2 weeks without food. Use a good, commercially available, beneficial bacteria product to get the filter going again.
Dealing with the parasites is a bit more difficult since we do not know exactly what the problem is.
Jungle Pond Products has good Ich medication that does not wipe out the filter. I would start with it. Keep a close eye on the fish and see if you can determine what sort of parasite they have. Tiny white spots like sugar is Ich and most commonly causes flashing.