Koi dying suddenly - Old bog water to blame?


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Our bog was shut down over the winter and today we were returning the plants and the old water was washed into the pond. The bog water was very smelly. The koi has started floating to the surface and 2 have died. We are putting the fish in a cooler with a bubbler and fresh water. Any advice?
 
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#1 reason we don't shut down the bog. That bad smell is a sign of low oxygen.

How big is your pond? How many koi? Do you have aeration in the pond? What do you mean you were "returning the plants" exactly?
 
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#1 reason we don't shut down the bog. That bad smell is a sign of low oxygen.

How big is your pond? How many koi? Do you have aeration in the pond? What do you mean you were "returning the plants" exactly?
We have harsh winters, so we bring the bog plants inside and turned off the water to the bog. 4500 gallons with 7 small koi. Aeration through the bottom drain aerator and waterfall. The "bad" bog water is no longer entering the pond. We are doing a 20% water chain right now. Any other advice?
 

mrsclem

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Do you have any cleanouts on your bog? I had a similar problem several years ago. Have a holding area below my bog that flows to pond. We did spring startup, bog was fine but the holding area was filled with rotted leaves. Lost 75% of my koi. I would do more water changes before putting fish back in. Watch for issues with the koi. We had a huge problem with fin and tail rot.
You can keep the plants in the bog if they are hardy, just don't drain the bog. Mine freezes solid but the plants come back.
 
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We have harsh winters, so we bring the bog plants inside and turned off the water to the bog.

I'm in the Chicago area - we know harsh winters. Bog plants (that are hardy to your zone) can be planted in the bog and left there. How are you removing them from your bog? Digging them up?

How is the bog water no longer entering the pond? I'm assuming you mean all the "bad" water has now been recirculated, but maybe I"m missing something.
 
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I'm in the Chicago area - we know harsh winters. Bog plants (that are hardy to your zone) can be planted in the bog and left there. How are you removing them from your bog? Digging them up?

How is the bog water no longer entering the pond? I'm assuming you mean all the "bad" water has now been recirculated, but maybe I"m missing something.
The bog overflows into the stream that leads to the pond. I have a dedicated water supply to the bottom of the bog. When I turn off that supply line, the bog no longer overflows into the stream.

We dug up the plants - Cannas, papyrus, that kind of thing. Probably not hardy for Salt Lake City.

We are changing out more water and I turned up the flow of the stream to get more circulation and aeration. Should I rinse my filter pads to help get rid of whatever came from the bog and is harming the fish?

I don't know if it is a related issue, but we were having a big algae bloom - pea soup, before the bog incident occurred.

Thanks!
 
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That bad smell could be sulfuric acid. It's very toxic, to people as well, and could build up in a stagnant bog. Did it smell like rotten eggs?
If we were to shut down our bogs or any filter for that matter and leave the water in there the lack of oxygen will starve out the bacteria and any organics and all start to rot . Again in the summer this starts after only a few days. But in the winter just like a refrigerator it takes much longer for things to start to decay.

So after 2 or three months the cycle has begun but often because of the temps its not a big deal but smelling rotten eggs is a sure sign you want to pump off the water and not throw it back to the fish. If you have another pump and a way to just move the water through the bog that's a big help in getting the bog back up and running
I should also mention that when I shut my bog down I run a air bladder/stone down the snorkel and let that runn all winter . I have also left it running all year to give the bacteria in the bog as much o2 as I can the more the bacteria gets the faster it grows, And works
 
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If we were to shut down our bogs or any filter for that matter and leave the water in there the lack of oxygen will starve out the bacteria and any organics and all start to rot . Again in the summer this starts after only a few days. But in the winter just like a refrigerator it takes much longer for things to start to decay.

So after 2 or three months the cycle has begun but often because of the temps its not a big deal but smelling rotten eggs is a sure sign you want to pump off the water and not throw it back to the fish. If you have another pump and a way to just move the water through the bog that's a big help in getting the bog back up and running
Thanks very much. This was our first winter with the pond. We clearly have much to learn.
 
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We're all learning @SaltLakeCity ! One consideration is to leave your bog running all winter long. If your pond (especially your waterfalls) are built to accommodate ice, you should be fine.

And yes, you're right - those plants would have definitely died off over winter in your bog. You may want to consider adding hardy plants that you can leave planted in the bog - much easier come fall to just let nature do her thing. I plant cannas for the pretty flowers, but don't really try to save them over winter - too much of a hassle for me. I pay about $10 for them - I figure they served their purpose all summer long!
 
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So, the fish we removed have revived in a separate tank. We thought 2 were dead, but they somehow recovered. We have one dead small fish and have 3 we have not found, as the algae bloom is severe and we cannot see to the bottom of the pond.

We are hoping to get the beneficial bacteria going again to address the algae bloom
 
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We have chosen to take the organic/ natural way of keeping our fish and ponds. This comes with all the quirks mother nature has to offer good and bad.
Adding some start right or any product with some aloe in it will benefit the fish. About the only time I add to my water. Preferably in a hospital tank.

Which is next for me to build a hospital tank. So if something starts to show I can treat the fish prontoe
 

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Save the money on the beneficial bacteria, as at best it is useless, as the bacteria is already present in your pond, and will expand to Consume it’s available food source be it ammonia, nitrites, etc. Besides it won’t do much for the algae bloom, agree with everyone else, patience it will clear on its own. Also, as was said numerous times consider leaving the bog running year round from now on.
 
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Thanks. I will be changing the bog a bit to allow year-round use - there is a low side that is prone to losing water. We have saved 3 of our 8 koi and are starting over with a full water refresh as whatever is killing the fish from the bog seems to still be present after a 50% water change - we put one koi back in and it died. The bright side is that my wife now knows all the ins and outs of the pond and is very interested in participating going forward. Anyone selling koi in the Salt Lake area?
 
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I strongly suggest posting some pictures. It would be the first time it showed ahhhh there's your problem
 
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mrsclem

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Make sure if you are using tap water for water changes to treat for chlorine and chloramines. Also, check the Ph of your tap water.
 
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