An unexpected crisis has occurred in my 1600 litre Koi pond recently, in that after 2 years of having excellent water quality (ammonia and nitrite at 0 ppm as well has a optimum nitrate and pH level), my ammonia level has suddenly started to spike at 2 ppm (as recorded 2 days ago). Over the last 3 days I have been arduously taking around 50% of the water out of this massive pond using a 10 litre bucket. In doing so I've been trying to feel with my hands around the pond shelves and pond base for anything that is dead and perhaps rotting to an avail. I've had a high powered pond vacuum in the pond on the presumption that the minuscule amounts of plant matter may be adding the ammonia level, but after having removed all of this on day 1 and still have the ammonia level increase further, I can safely rule this out as being the cause.
On day 2 I chose to remove 5 floating pond baskets that were planted up with a total of 5kg of pond soil, pea gravel and of course various plants. I removed this on the belief that the powerful air stones, that I have only just situated directly beneath these floating baskets, may have pushed some of the ammonia out of the soil and into the water column. After removing this soil and doing a 50% water change my Seneye ammonia sensor light went off, indicating that the ammonia level was normal.
It is now day 3 and the Seneye ammonia sensor has come back on and my API Master Test kit is giving a reading of about 1.5 ppm of ammonia and 0.25 ppm of nitrite.
While it would appear that the ammonia level is lower than the initial reading of 2 ppm, I do NOT understand how the reading could become safe after doing water changes (and soil removal) only to then go back up to 1.5 ppm. Does anybody have an explanation for where this 1.5 ppm of ammonia has come from? I will point out a few facts to help with your answer:
Note: the fish have not been eating for 4 days now. They are swimming very slowly on the base of the pond and I fear they could die.
On day 2 I chose to remove 5 floating pond baskets that were planted up with a total of 5kg of pond soil, pea gravel and of course various plants. I removed this on the belief that the powerful air stones, that I have only just situated directly beneath these floating baskets, may have pushed some of the ammonia out of the soil and into the water column. After removing this soil and doing a 50% water change my Seneye ammonia sensor light went off, indicating that the ammonia level was normal.
It is now day 3 and the Seneye ammonia sensor has come back on and my API Master Test kit is giving a reading of about 1.5 ppm of ammonia and 0.25 ppm of nitrite.
While it would appear that the ammonia level is lower than the initial reading of 2 ppm, I do NOT understand how the reading could become safe after doing water changes (and soil removal) only to then go back up to 1.5 ppm. Does anybody have an explanation for where this 1.5 ppm of ammonia has come from? I will point out a few facts to help with your answer:
- The pond has been established for 7 years and it was cycled properly 7 years ago.
- 5kg of pond soil was in used up until Friday 19th June. On Saturday 20th June, ammonia rose from a safe level back to 1.5 ppm.
- There are no dead fish, frogs or other animals in the pond.
- The filter media has not been cleaned with untreated tap water or disturbed in anyway.
- I have not added additional fish to the pond (so I have not added to the bio load)
- I have not fed my fish more than I normally do.
- I have placed zeolite in the filter to help reduce the ammonia level
- I have done 3 50% water changes over 3 consecutive days.
- My tap water ammonia level is 0 ppm.
Note: the fish have not been eating for 4 days now. They are swimming very slowly on the base of the pond and I fear they could die.
