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Hi, Tony
Searched through your articles to find an answer to ammonia buildup. While we were away some friends overfed tour koi leaving massive amounts of food. The water had turned green and smelled of ammonia. I have been doing water changes daily. This is the fifth day> Should I continue or am I stopping the bacteria from developing?

Eric

If the ammonia level was a bad as you imply (smell) the fish would be dead already. The biofilter should have removed ammonia within hours if working properly.

Again assuming you are correct and biofilter is not working then you need to do massive water change

Hi Tony,
Thanks for the advice. In fact we have lost about five of our largest Koi who have been with us for 14 years. I have been changing about a third every day. The tests show that the ammonia is lessening and I can see almost down to the bottom I just wasn't sure whether to continue as I thought i might stress the fish even more and disturb bacteria developing in the filter.

When I arrived home from holiday and found the situation of masses of food floating green water and fish gasping I immediately did a water change (about a third) and cleaned the filters. Upon taking the filters out I discovered a white fungus on the filters. Someone suggested that the 'friendly' bacteria might have been killed off.
Your help is appreciated. It has been a learning curve.
Regards Eric


Hi, Eric … I have no idea what the white fungus is but I’m pretty sure it wont stop the filter working. You cannot wash bacteria off the media inside the filter. You should consider adding extra biomedia into the filter if you have space. If you can add air to the pond and filter this will help. Don’t feed for a few weeks