Hi Bill,
The questions are answered here. The Pond is not like some lakes it is in the back yard 17X10and 4foot deep in middle with shelving. The largest fish may be 8 or 9 years old. The ones dieing are the smaller 1 year or two year ones 4-5 inch and these are Gold Fish that were bought as Feeders. The ones dead are generally in the 6PM hour when I get home. Shade- the pond is substantially under a large tree so it is shaded some part of the day. No algea bloom as the filter and sterilizer takes care of that- the water is pretty much crystal clear except when the bottom is stired up- there are leaves and rock pushed in by raccoons over time at the bottom- I have to do a one armed push up to get the rocks out of the deep area. I do not use chemicals except the Chloramine,Chlorine nutralizer since the fish death and since adding much tap water. It rained last night.Aeration pump was not running 24 Hrs but is now more so.Temp is at 25 degrees C presently.