timber said:
did a test on the tap water this morning and these are the results
GH = 30
KH = 30
PH = 7.0
No2 = 0.5
No3 = 40
no more deaths this morning, my current stock is. 1 x 6" Koi. 2 x 4" ghost koi. 2 x 3" Goldfish 2 x 3" Shubunkins, and 3 X 3" Blue orfe
Total of 10 fish.
Timber, if your tests are correct and this is your tap water, then, personally, I would still continue to do water changes due to the high fish density with poor filtration, but, to make sure, you really need to do an ammonia test.
Otherwise, to address the .5ppm Nitrite, assuming the test is correct, then I would recommend you using a water detoxifier product, that neutralizes Nitrite amongst other stuff, so we can get the Nitrite under control. A good detoxifier is
AmQuel Plus. There are other products out there that likely work just as good so you might need to go to your local fish store to see what they have available. If the detoxifier product is too expensive, then you will need to look into increasing the water's salinity to
.10%, at the very least, and the procedures and cautions are discussed quite well in the thread,
First Time High Ammonia; absolutely be sure you read the entire thread before adding any salinity; if done incorrectly, then this could cause more problems.
Once the Nitrite is neutralized, then you will need to improve your biological filtration.
There are many ideas on this forum and elsewhere, but I will list a few options that may help you get jumpstarted. There is the
DIY koiguy skippy filter, a
DIY trickle tower, and you could also build your self a bog in a seperate container where the water gravity flows back into the pond.
If you want something simple, then look into the retail pond store products that sell a biological filter
with the keywords "wet/dry" or "trickle" such as
Tetra's gravity pond filter.
To start out easy, you can try adding alot of nutrient soaking plants, which will also give more area for bacteria to grow to neutralize the Nitrite. Look into using Water Hycanth, Water Lettuce, and also some rushes/sedges. It will take a few weeks for these plants to complete their transition, but, once they do, then they will do the job.
So, all this and also reducing the fish population.
First is to improve your water quality.
Then, you can look into other stuff such as if it is bacterial, parasitic, or a pathogen.