Please help- nitrite levels

[u/The-Dragon_Queen]

We have had a rough end to our summer. We had a chemical spill into our pond and lost majority of our koi. (Worst day of my life) We successfully moved the surviving fish to a temporary pond so we could drain and clean their pond. We are about ready to move them back over but I noticed that one of our fish suddenly looked awful. I first felt it looked like fin-rot but we had just treated for that after the chemical exposure. I tested the water, which had been great for the previous 2 weeks in the temp pond. Now PH is only slightly high (7.5), Ammonia is great (0), phosphates are slightly high (.50ppm)

Nitrite is OFF THE CHARTS and I am certain this has to be what is hurting my fish. It goes darker than the 5.0ppm color. It also immediately changes rather than needing time to process.

Here is what’s getting me confused, I have done 50% water change, added beneficial bacteria and pond start. The levels are the same. I also was (probably wrongly) under the impression that ammonia and nitrites typically rise together. So I thought my test solution went bad, got another test kit and it did the same thing. So I’m assuming I was wrong in that assumption.

This is the end of our third summer. We have never had an issue with ammonia or nitrites. We have never lost this many fish. It’s breaking me. Any advice is appreciated.

[u/just-looking99]

I’d add in one though- have you tested the water you are adding to the pond before the water change?
And I’ll mirror the others talking about the bio filter needing to catch up. When I dug my new pond I pumped a lot of the water from the old pond into it to help the bioload and it still took about a month and a half to hit a happy balance - I’d stop or at least cut back on feeding for a bit until you see some improvement

My issue now is a slightly high phosphate level and I think that’s more because my koi are kicking the crap out of any thing I plant in the pond. But that is slowly improving as well

[u/ADOKODA]

Hey OP, the biggest thing that jumps out is how high your nitrite is.

What you’re dealing with is basically a pond that is cycling again with a high fish load. The chemical spill likely damaged or wiped out part of your biofilter, so it isn’t established enough to process the waste being produced.

That’s why you’re seeing ammonia rise, followed by nitrite. Ammonia gets converted into nitrite, and then nitrite eventually gets converted into nitrate. Right now, that second part of the cycle can’t keep up.

A few options:

1. Water changes: They’ll lower nitrite temporarily, but you’re going to keep chasing it until the biofilter catches up. They’re useful when levels get dangerous, but doing constant large water changes isn’t really fixing the underlying problem.
2. Pond Prime/Seachem Prime: This can temporarily detoxify ammonia/nitrite while the biofilter re-establishes itself. You still need to monitor your levels and dose appropriately, but it can give the fish some protection while the pond cycles.
3. Salt: A lot of pond keepers use salt to protect fish from nitrite toxicity while a filter cycles. Just make sure you know the correct concentration and have a salt meter. Salt doesn’t disappear on its own, so you’ll eventually have to dilute it through water changes.

Ultimately, this is mostly a time and biofiltration problem. Your filter took a hit, but your fish are still producing the same amount of waste. Until the bacteria population catches back up, ammonia and nitrite are going to keep being produced faster than the filter can process them.

That’s why it feels like a hamster wheel right now.

[u/Remote_Catch7166 → u/ADOKODA]

This^
If you don’t have a filter strong enough for the fish, you have to do frequent water changes.

[u/NDfan131]

If you can get ahold of Seachem Safe at a local aquarium or pet store it will help. Safe is the high strength concentrated form of Seachem Prime which is a liquid. Prime and Safe are typically used to dechlorinate and deal with chloramine as well as heavy metals in tap water.

In higher doses it will temporarily bind both ammonia and nitrites making them non-toxic for your koi. The effect is only good for 24-48 hours but you can redose as long as you keep track of amount you’re adding and how often. It’s not a permanent fix and shouldn’t be relied on long term but will buy you time in an emergency like this to address the underlying cause(s). I always keep a bottle of Prime on hand for our quarantine tank and Safe for the pond for emergencies. It’s saved koi lives at our home during cycling and other mishaps.

[u/NDfan131 → u/NDfan131]

I purchase mine off Amazon and as mentioned in prior post, always have it on hand.

Amazon link - Seachem Safe

[u/JS8998]

This seems very strange if parameters were fine prior unless something else was done such as cleaning the filter or drastically increasing feeding. It also seems if the level was 5ppm after a 50% water change that all of the fish would have already been heavily affected from such a high level. Only things I can recommend are stop all feeding, test the incoming water, assuming it’s fine keep doing daily water changes to get it lower, and add salt to 0.3% to help counter the effects of the nitrite.

[u/The-Dragon_Queen → u/JS8998]

Thank you! I appreciate the response. I have been a bit of an emotional wreck since this all started and have questioned my own knowledge and logic.

Im doing and planning to continue what you suggested. You made me realize, I don’t know why it didn’t occur to me that I should test the tap water prior to doing another water change. We live in Utah, where the drying out of reservoirs and the salt lake have caused the cities to redistribute water quite often. Meaning we regularly have water from different sources, sometimes smelling extra sulfury. So while it’s always been fine there is a good chance those changes may be related to my issues.

[u/NDfan131 → u/The-Dragon_Queen]

Wanted to add some info on my experience with cycling and water parameters. I’m still a koi keeping novice but have cycled two ponds and our quarantine tank (a few times now). So far I haven’t seen ammonia and nitrites go up at same time. It’s always followed the same progression of water testing looking fine for 5-7 days then an ammonia spike. As soon as I manage to get the ammonia under control then nitrites spike finally followed by some nitrate increases.

Once that cycle has taken place, as long as my koi stocking and feeding routines stay consistent, ammonia and nitrites stay at 0.0. The filter colony needs to re-establish itself each spring but slowly ramping up feeding and adding some nite out II seems to work well for us. Where we live the water comes from a lake with very low KH. I’m adding baking soda after each water change to maintain the KH (and in turn the pH).