I agree and wonder too. In a 3000 gallon pond those 7 comets could not possibly be producing that much ammonia. So, you need to look elsewhere. I would look at the filters. They may be overwhelmed with residue from dead bacteria and other debris. Did you do a test for buffering capacity? That would be KH. My new test kit for some reason calls it High Range PH. Maybe I need a different kit. KH measures the capacity of the water to resist changes in PH. This is important because rapid change is harmful to the fish. I learned a little from a former poster who I really wish would come back. He would know in an instant what was going on while I am simply looking at my own experience. Fill a container with the new water from the tap. Allow it to sit overnight to let some of the gassy chemicals like chloranimine to dissipate. Add pond water. If it was something added to the tap water it should remain clear. That means KH is high enough to cause the pond water to react to the chemicals in the new tap water by forming a precipitate. All will probably be well in time. To eliminate the problem or reduce it you can add air with a bubbler or a fountain, increase turbulance, let the tap water sit overnight or use a chemical to counter the chemicals in the tap water. If the KH is too low, there are chemicals you can add but a little trick I learned is to put slugs of Plaster of Paris in the pond. It will react to the PH of the pondwater by slowly disolving. The term is something else but to the eye it looks like disolving, so that is the term I will use. The POP is being reformed by the pond water to achieve a certain level of PH. If the PH is too high, the POP will disappear quickly and the PH will get lower until it reaches a balance which by happy chance is the best level for the fish. Once a balance is reached there is no more or a reduced level of reaction. Leave the slug in the water so it will react to changes you don't notice. It won't be harmful and ammonia levels will also be reduced. I mold POP in the shapes of bubbles or starfish just to make them look like decorations. I don't have any problems with PH since I started doing this. If you use this trick make sure the POP does not have any additional chemicals added. Dap sells one that is pure POP. I wish someone else with a better handle on chemistry would post, please. I am not the best person to expain all this. A forum search on POP or plaster of paris should be helpful. Sandy

Chas.. Yes, they do look like the ones on the GEICO commmercial except mine are MUCH fatter because they have such wonderful plants to eat. hahaha I laughed myself silly the first time I saw that commercial. Really I love them, especially the babies, but it is funny to see morning glory vines with no leaves as far as the little critters can climb and blossoms at just the very top of the vine. Also squash and tomatoes with bites taken out of them are delightful surprises. In addition to the woodchucks, my sweet BF is now scalping the morning glory vines to feed a neighbor's pet rabbit. I gave up on sweet potato vines. The woodchucks go into some kine of rapture when I plant them. I swear they have learned to levitate to get plants they like. Anne

Cameron, I had forgotten about your stream. I couldn't remember your blog name but I searched for your stream on Cottege Garden. Even more georgous than your other great seriously thought out designs. I pretty much just plant what I hope I can keep alive. The impatiens self seed and I spread them around a little. My biggest success or surprise was/is Verigated Sweet Flag. It is the spikey yellow-green grass like plant. It grows IN the stream but will perform in well watered soil. I got a pot at a garden/pond store. It has multiplied a hundered fold.

Nice overview. I would also recommend BACI's hydroponic FAQs for more detailed information. These are available by doing a search in this forum for "FAQ".