Nitrate battle


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Ok, so we are newbies. We installed a 300 gallon pond semi in-ground using a galvanized stock tank from Tractor supply. We installed a Pond Max SF650 all in one filter. We have a few plants and treated the water for chlorine before introducing the fish.
so far so good, started with 2) 5” koi and 1) 4” fancy goldfish that had been established in our parents pond then added 2) 2” koi and 1) 2” goldfish. They were thriving and we even trained them to come up to eat at feeding time by wiggling our fingers on the water.
I do know that algae on the bottom rocks and sides are healthy, but the water became a little cloudy and green. We added an algaecide and it cleared the water but became foamy for a few days. One is the koi committed suicide and jumped out (sad). At this point we thought it was just stress from a new environment. Fast forward about three weeks and the fish became reclusive we lost another two the same way. Quickly got a test kit and all levels were good except nitrite was very high.
we don’t want to lose the two fish we have left so first I did a 25% water change (adding the proper amount of stuff to eliminate chlorine) and added pond salt. Test results were the same! first we suspected some miracle grow got in there but once the water was changed twice the test results were the same. After much research we discovered that the decaying organic matter from the algaecide application could elevate the nitrite levels. Tonight I changed out 50% of the water and put in another dose of salt. The nitrite results are now about .25 which is much better but still not where it should be. Hopefully the salt will kick in and tomorrow we will have a normal test, good news is they are swimming and eating for the first time in a week.
Does anyone have the same experience with elevated nitrite after an algaecide application? We are hoping we solved the problem.
Just to show how much we racked our brains, we even tested the runoff from the shade sail we installed over the pond thinking it may be leaching something into the water, but the runoff water tested 0.
 
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Welcome to the forum :)

I'm not 100 % sure, but I don't think galvanized tanks are good for fish....I believe they leach something....maybe zinc? Something to look into.

You can find information about the nitrogen cycle on the internet. If you have high nitrite, your pond isn't fully cycled. How long has it been up and running.

Not to rain on your parade, but 300 gallons is way too small for koi. They grow fast and also create a lot of waste. I think most of us here do NOT use algaecides. You need patience for the pond to cycle, plants, water movement and aeration.

Why are you using salt?
 
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Welcome to the forum :)

I'm not 100 % sure, but I don't think galvanized tanks are good for fish....I believe they leach something....maybe zinc? Something to look into.

You can find information about the nitrogen cycle on the internet. If you have high nitrite, your pond isn't fully cycled. How long has it been up and running.

Not to rain on your parade, but 300 gallons is way too small for koi. They grow fast and also create a lot of waste. I think most of us here do NOT use algaecides. You need patience for the pond to cycle, plants, water movement and aeration.

Why are you using salt?
 
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Welcome to the forum :)

I'm not 100 % sure, but I don't think galvanized tanks are good for fish....I believe they leach something....maybe zinc? Something to look into.

You can find information about the nitrogen cycle on the internet. If you have high nitrite, your pond isn't fully cycled. How long has it been up and running.

Not to rain on your parade, but 300 gallons is way too small for koi. They grow fast and also create a lot of waste. I think most of us here do NOT use algaecides. You need patience for the pond to cycle, plants, water movement and aeration.

Why are you using salt?
Thanks for the quick reply. Using pond salt because I read that it is effective to quickly reduce nitrite levels when they are at a toxic level for the fish.
we did research before using the steel tank and found no negative effects.
 

Mmathis

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Hello and welcome! I don’t want to beat a dead horse, but 300 gallons is too small for koi. Goldfish, yes, but not koi. Therein lies your problem. Someone has already mentioned the potential problem with a galvanized tank. Also mentioned is the use of chemicals such as algaecides. They are only treating a symptom — the algae — but aren’t taking care of the “disease.” Algae, high nitrites and ammonia are caused by a biological filter that hasn’t fully cycled, or that is overloaded. Fish produce waste that is broken down by the beneficial bacteria that naturally occur in a pond environment (read about the nitrogen cycle). If there is more waste produced than the bio filter can handle, the algae steps in (as a plant, so to speak), and you get funky water. Also, though not exclusively, when fish start jumping out of ponds, it’s usually because they are trying to get away from a toxic environment of excess ammonia and nitrates, or from a parasite infestation.

Koi and goldfish produce a lot of waste. Right now those koi are small, but they grow quickly.

And when we say that we don’t recommend the use of chemicals, it’s because chemicals are just a bandaid — they temporarily mask a problem, but they don’t cure the problem. You have to fix the problem if you want to have a balanced pond environment. For now, I would recommend that you do several small water changes (use de-chlorinator). Continue to monitor your water parameters. Give your bio-media a chance to catch up. Don’t feed your fish for the time being. Don’t worry, they will be fine. And last but not least, you may want to consider re-homing some of your fish — the koi in particular. Rules of thumb aren’t carved in stone, but the recommendation for koi is a minimum of 1000 gallons for one koi, and 250-300 gallons per additional koi.
 

IPA

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Reading these types of posts make me upset. Sorry to the OP and welcome but the fish that haven’t already died will probably not live a full happy life if they don’t all die in the first year. First, adding salt to a metal container is just going to leach out more zinc in this case. I understand why it was done. I would not add more at least once you are through this immediate crisis. Also, no algaecide period! Second, the nitrite is high because that is part of cycling a tank or pond. Third, way too small a container for koi. Fourth, besides being too small, just about anywhere in the world with a metal stock tank above ground it’s probably going to be way to hot in the Summer months.
Addressing the metal tank, get API chlorine & heavy metal neutralizer. Addressing the nitrites, do 10% or more water changes daily using the neutralizer. Good you have a way to test so test every day before and after the water change. Nitrites are more deadly than ammonia at the same levels. The tank will eventually cycle given proper biological filtration media is used. Don’t rinse filter media unless is is getting clogged up and only rinse it half way or half at a time with dechlorinator water. Addressing koi, once through the cycle period they may be fine for the short term, consider rehoming or building a 2,000 gallon pond. Personally I’d purchase a large container to move them temporarily and most of the water to so you can purchase a liner for the stock tank. Normally we do not recommend PVC liners but in this particular case it will be a huge improvement to not having one at all. Try to keep it shaded and look into adding plants but know buy adding a lot of containers in the tank you’ll also be displacing water. Good luck.
 
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The fish may be jumping out because they are trying to escape the condition of the water they are living in. They are in a toxic environment.

Salt does not eliminate the nitrite. It can protect the fish from taking up the nitrite into their blood stream and causing brown blood disease which is fatal. But the tests will still show the same level of nitrite in the system. That will not go away until it has been converted to nitrate by the beneficial bacteria that must be established. That takes time, usually a couple of months for the cycle to complete.

It seems that you are going through the nitrogen cycle and you need to read up on that as mmathis has already been mentioned. And yes, adding salt to a metal tank is not a good idea and metal tanks are not good to start with, as others have said.

If you can get Prime conditioner, made by Seachem, it will help to protect your fish from ammonia and nitrite, and it will dechlorinate the water, too. It will only be effective for 48 hours for ammonia and nitrite, so it will have to be dosed regularly at that interval.

If you have to use a metal tank, it would be good to get a pond liner to put into it and keep the water from interacting with the metal.

The general rule for koi is that they need AT LEAST 250 gallons per fish. Some people swear that 500 is the right number and others want to have 1,000 gallons for each fish. Your tank is much too small for the fish you have in it.
 

Mmathis

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Also, though not exclusively, when fish start jumping out of ponds, it’s usually because they are trying to get away from a toxic environment of excess ammonia and nitrates, or from a parasite infestation.
I meant to say ”nitrites” instead of “nitrates.”
 
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When it comes to ponding, patience is needed. Nothing happens overnight. In most cases, if you leave it alone and let nature do its thing, everything will be fine as long as the conditions were correct in the first place.
You need to correct a few conditions as others have stated.

A pond as small as yours is actually harder to keep since there is so little water. Any of the parameters can change quickly.

Agree with everyone....
Get those fish out of that galvanized tank. Temporarily house them in something like a kiddie pool. Lay a liner in the tank to separate the water from the zinc.

Build a larger pond or rehome those koi.
Stop adding algaecides and salt. If you have a sick fish you can quarantine it in a separate container with salt added, but don't salt the whole pond.

Read up on the nitrogen cycle as suggested.
Give your filter a chance to colonize with beneficial bacteria.

All my water changes are done by nature when it rains. If you live in the desert and have a lot of evaporation, then you'll need to add water.
 
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