What killed the comets?

[Pleco1415]

I had 4 comets in my backyard pond for the past 6 months. I've had the fish for many years and I've always brought them in for winter and out at spring. Today I went out to find all the comets dead. The only survivor was a pond loach that I have also had for quite some time. I recently did a water change on the pond, the regular 25% every 2 weeks. My town recently did a clean of the water systems and I'm wondering if that is related. I tested the water and this is what I got. Way off from the norm

 

[gemach7]

What test strip do you use? How many gallons is the pond? Also if they did a water system flush the chemicals used would not show up on your test strip. Do you use water conditioner? When they do a water flush they add more treatment chemicals chlorine/cholarmine. A relatively small amount of either can kill fish. Besides these small amounts of metals present in the water pipes can leach into the water. When these reach certain ppm they can also be deadly.
During times my town says they are doing these I skip a water change on my tanks. A small amount of nitrate is less dangerous than high amount of say zinc.


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[Pleco1415]

What test strip do you use? How many gallons is the pond? Also if they did a water system flush the chemicals used would not show up on your test strip. Do you use water conditioner? When they do a water flush they add more treatment chemicals chlorine/cholarmine. A relatively small amount of either can kill fish. Besides these small amounts of metals present in the water pipes can leach into the water. When these reach certain ppm they can also be deadly.
During times my town says they are doing these I skip a water change on my tanks. A small amount of nitrate is less dangerous than high amount of say zinc.


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I'd say pond is about 60-80 gallons, I try to keep it as natural as possible no water conditioners or chemicals. You could reprimand me if I ever did this to my aquariums but the water outside from the hose is suppose to be non treated and it always has been. I've never had this issue before with the outside water. I'm not sure what test strips I use so I'll just post a pic of the colour chart on the back.


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[Pleco1415]

I forgot to ask, the pond is under a chestnut tree and occasionally a few will drop into the water, could this have any effect on the fish?

 

[gemach7]

I forgot to ask, the pond is under a chestnut tree and occasionally a few will drop into the water, could this have any effect on the fish?

Horse chestnut twigs, buds and seeds are poisonous. This is the most common form planted in backyards as American chestnuts are endangered.

I would make sure your hose water is well water. If it's connected to city water it contains chlorine, chloramines or both.


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