Koi problem, possible water chemistry problem

[hgi]

I friend ask me to look at their Koi's yesterday saying that they were dieing unexpectedly. The pond is 3x90g Rubbermaid pond totes things linked together, no plants, hooked up to a canister style filter that looks to be about 1000g/hr. The Koi in question looked to have fin rot and some white fungus on their body but are still very active. They have a pond test kit but it only had liquid test for ph/kh/ammo/nitrite/co2. The pond has 3 water falls(lots of surface disturbance) from tote to tote, so I know it has nothing to do with co2.

They said they had the water changed by a company the day before, not sure how much water, I asked if anything was added to the water, they said they added some type of meds (no idea what kind) and that they added some salt. I did not open the filter to see what was inside of it as I didn't want to go that far yet.

Today I went there in the morning before work to test the water with my kit and got 0-0-0, ammonia-nitrite-nitrate, this seems weird to me as I'd expect to see some readings, especially some nitrates. Another thing that is weird to me is they have gold fish in the top two totes and koi's in the bottom, none of the gold fish seem to be infected in anyway.

My lady didn't have time to get photos of the fish today, so I'm hoping that I'll be able to post some photos of the koi's tomorrow. Also because of the weird test results I'm going to give the pond a few days and test the water again on Friday morning and hopefully I get a some readings.

Right now I'm thinking that who ever did the water change disturbed the filter by not turning it off, filled the pond up with tap water and sent the pond into a mini or possibly a full cycle again. I noticed a old black garden hose in the sun beside the pond, I ask and it was used to refill the pond.

Any suggestions on what to look for would be awesome, and I will also try to provide as much info as I'm able to.

Thanks.

[Rastapus]

Hardness would be the first thing. Koi prefer VERY hard water as do Goldfish. Yes for sure 0 on all levels, impossible unless they changed all the water 5 minutes ago.

[hondas3000]

To me if the test is 0-0-0 that mean its is cycle, what I would do in this case is clean the filter media and add medication to the right diseases. Which you need to judge exactly what diseases is it. Fin rot and fungus not a deadly disease but its need a right medication for it.

[Rastapus]

Several medications become toxic in a very soft water environment, I would test the hardness before medicating for sure.

[Algae Beater]

most issues with hardwater fish can easily be remedied by maintaining proper water parameters ESPECIALLY GH and KH (general hardness and carbonate hardness)

get the right buffers and you will notice a difference.

[hgi]

I'll go check the water's PH/GH/KH tomorrow after work when I go take the photos cause I doubt the lady will have the time to do it. I know Nanaimo's tap water is about 6.8ph, though I remember it dropping down to 6.2ph in my tanks after a week, I don't know or believe there's anything in the pond to buffer the water as it's a bare pond, so unless there's a buffer in the filter....


A quick google search I'm finding that Koi's prefer

pH 6.5 -9 (what's most common area? mid 7's?)
Carbonate Hardness/Alkalinity 50 - 170 ppm
hardness 75 - 150 ppm

I'll post up the results and hopefully photos tomorrow.

Thanks for the heads up.

[hgi]

Alright went by the pond today,

First off I want to point out that their liquid test kit is weird, I've never used one like this before or seen one.

Anyways the GH and KH says to add one drop at a time till it turns from red to green, well it went strait to green.... then the other one was blue to yellow, it went strait to yellow...

I took some water home with me and tested the pH with my liquid kit and got 7.6,

here's a photo of one of the kois, after looking at the photo it looks like a bite to me, are koi's known for nipping? They're about 3" to 4", how often should they be getting fed?

Anyways here's a photo.

[Rastapus]

Those results mean your hardness is 0 for both GH and KH, same as our issues in the LML. Salt will raise the GH and Alkaline Buffer will raise the KH. I would go at least 7 degrees on both. Koi will tolerate pH anywhere between 7 and 8.0 and even higher. You pH is very unstable with hardness that low. As far as the photo goes, is there more then one koi in that condition? It is likely a bacterial infection brought on by the water quality. Add buffer and salt, then treat with an antibiotic such as Erythromycin or Tetracycline.

[hgi]

Umm, not really, there's maybe only 1 or 2 more Koi's that are in that condition.