Lost my whole school today

[PapaBear]

I really hate this for you, as you have obviously worked hard to prevent this, but the more we read the more it begins to look like a "perfect storm" situation.

A heavily stocked pond with ph on the low side of comfortable.
Kh value likewise on the low end of the scale.
A very low ph fresh water supply.
Recent spawning activity causing added bioload to the filter.
Filter washed from a garden hose either killing off much of the bio from chlorine (if municipal water) or from acidic wash water (likely if from a well laden with acidic CO2)
Add a nice bit of acidic rain to the mix and multiple crashes in kh, ph, bio were almost inevitable.

A few suggestions.
Test your tap water again after letting it rest for a few hours for both kh and ph. I'm betting the 6.0 ph will rise to around the 6.8 you have in the pond.
In the future pay closer attention to Ammonia and Nitrite, and less to Nitrate. The first two pose an immediate health risk to Koi, while Nitrate is far less an issue.
Since your water runs on the acidic side monitor your kh religiously, and try to maintain it above 125.
In the future, rinse your filters with pond water rather than from the hose. That way the bacteria will not be exposed to either chlorine or highly acidic conditions.
I hope all of this helps you to have a better future with Koi even though the lesson has been painful.

[JasPR]

Larry this is very good advise for the beginner pond keeper to follow. But not good advise for the established koi keeper.
Why would I say that? Because the 'philosophy' behind the advise is not the proper perspective.
Here is the contradiction- low alkaline reserve is dangerous in a pond lacking in some parameter or husbandry routine - stocking, feeding technique, circulation rate, filter size and design, maintenance routine, etc. And we associate soft water typically with a low alkaline reserve. BUT koi LIKE neutral'ish' water and they like soft water- the flourishing in such an environment is seen in skin, growth rate and appetite.

I was attempting to lay out to our poster that a dynamic was in place and the steps of that dynamic. You correctly identified the stocking rate. Don correctly sniffed out the likelihood of the pH crash. And the trouble maker Renfield, from the other parish tried his best to embarrass us all with suggestions that somehow we all missed the high ammonia reading. But the truth is, this is all a time line and a cascading event.
You 'could' blame the water itself. A water likely high in carbon dioxide out of the tap ( never did get that intermediary pH reading after aeration) is not 'bad water' . And a neutralish pond is not a bad environment ( in fact it is potentially excellent). It is the other parameters that are testing and straining the situation. And those parameters are - 1) stocking and 2) water changes. A pond stocked to that level and fed well is a threat to that alkaline reserve. Therefore the water changes need to be more frequent and all excess organics must be removed daily. The poster's aeration seems good but I'd have to see the circulation rate and waterfall impact. I'd definitely add a TT to this system. And I'd only stock 8- 10 koi in 2000 depending on size. I would also do a weekly Saturday morning water change in the range of 20% of the water in addition to daily sump cleaning during the feeding seasons. This is now addressing the cart and not the horses behind it! Hope I made myself understandable here? JR

[PapaBear]

JR, I agree wholeheartedly, but the pond in question sounds more like a WG/Koi pond compromise, so my advice centered more on survival than excellence. A nice TT on the pond AND the water supply (for degassing CO2 up front) running a slow flow through water exchange would be my preference, but then again so would removing the plants and I doubt that will happen (right away...)

[JasPR]

I agree, that survival is the only reason for the bandaid approach and emergency intervention. A focus on the horses behind the cart, so to speak.
But the fish are gone now. Maybe it is time to enlighten a water gardener, and at least spell out the futility of placing too many koi in a water garden setting- especially if they have done Ok to a point, and are now bigger. From there understanding could lead to a big picture understanding of proper koi keeping and a proper fundamental philosophy.
Water gardeners biggest hurdle is to see emergency remedies and 'patches' to a system as just a management of symptoms. And not a technique for true koi keeping.
I know you agree. So we somehow have to be patient but constantly offer ' the better way' JR

[KoiCop]

Hello Veronica . . .

Bumping for readings:

Originally Posted by KoiCop

What I'd like to see you test to confirm a pH Crash and not some other dynamic going on:

pH from tap AND from pond
KH from tap AND from pond
GH from tap AND from pond

Also, is your water from a well or municipal water? If well water, we'll also need intermediate readings of tap water after it has been aerated but before being added to your pond.

Best wishes,

[cppond]

Originally Posted by cppond

I'm sorry, is this a current reading?

Originally Posted by JasPR

And the trouble maker Renfield, from the other parish tried his best to embarrass us all with suggestions that somehow we all missed the high ammonia reading.

See, JR, this is why I cannot accept the things you say as true. All I did was try to draw attention to the ammonia reading so someone would comment on it and you completely mis characterized what I said as "trying his best to embarrass us all with suggestions that somehow we all missed the high ammonia reading." Your representations of the things I have said or done have little relationship to reality. Why should I believe that your representations as to what others have done is not likewise distorted? I didn't make any "suggestions" and said as little as I could so as not to provoke another attack from you and others. I am sorry if you felt embarrassed or somehow provoked by the seven words I posted.

[Tamianth]

Hi Veronica,

I would suggest here that the strips are ok, but you get better accuracy with drop kits.

[JasPR]

Carl, please don't start this again. You must be a pretty busy guy administering to your 9000 plus member on your board and in your International internet society. And I'm sure you can do a lot of good over there for those having pond problems, so how about NOT seeking out the one thread I'm currently helping on to throw in the digs? I mean, is that too much to ask? You gotta wonder what possess you at this point? JR

[JasPR]

Honestly I wouldn't use the strips. Good for a quick and dirty reading, but as Tamianth has pointed out, with the drip kits around and easily attainable, they are really prferred for their greater accuracy. Having said that, they are really only as good as the human eye and technique. Meters are pretty good if you can afford them and keep then tuned.
What I like to do/have is two drop kits and if one gets a disturbing or shocking reading, use the other kit to confirm that. It is actually helpful to have kits from two different manufactures for this kind of confirmation.
And of course, it pays to throw these kits out after a period of storage and buy fresh reagents. JR