Thanks all so much for the replies. So sorry for lobbing our the desperate cry and then being silent...much going on here on top of the problems with the koi pond.
I’ll try to answer all the questions in chronological order of the posts, which will hopefully help clarify our setup and the current situation.
Test kit: I do not have a test kit. I was using pool test strips to measure PH. I was encouraged by a local koi supplier/pond supply store we found a couple towns away to use a liquid test kit. We got one and even after adding a couple gallons of vinegar over several days the PH in the morning is still 9+...it is maxing the scale out which goes to 9. That tells me the PH was and possible still is greater than 9 in the morning, and greater than that in the evening. This helps to explain why we have struggled with the algae so much this year. So though I’m told in this thread not to worry about it, I am going to continue to bring it more into normal range, like something stable between 7 and 8.4 or so between morning and evening.
Algae control: we have added a nominal amount of algae control granules we got from Webb’s Water Garden online several times this season, but not for many weeks.
Pond size: yes I am confident of the 3000gal size. The pond is oval shaped, about 20’ x 15’ and 1.5’ to 2’ deep, and also features two good sized waterfall canals being fed by a Shinmaywa 10,500gph pump. We run the pump 24/7/365. Aeration is not the problem.
Location/recent weather/runoff: we are in Oregon in the Salem area...no storms to speak of (literally only trace precipitation for a couple months now), we do have lawn irrigation that is fed by our well, but the water is potable drinking water quality...tested last year. The pond is periodically topped off with this same water and partial water changes are accomplished by overfilling and allowing water to escape via an overflow drain that exits about 400’ away from the pond. It has been an unusually dry and warm summer for us so far.
Possible toxins introduced? I’m embarrassed to say, but a couple weeks ago we bought a couple small koi from a local chain pet store. One died within 24 hours. I’m feeling terrible at the though this may, along with water quality conditions, be killing our koi.
I will say there is a natural wetlands/swamp about 500’ away on our property and we occasionally have guest salamanders and frogs at the koi pond. This is not new this year. But I thought I’d mention it. We also used a lot of the little mosquito pucks in the pond this year to try and mitigate all the mosquitos. We have bats that visit the pond nightly to help with insect control. As of today a total of three of the large (I.e. about 16” long) koi have died. I think there is another for which death may be imminent. I’m starting to be able to see the ones that are at greatest risk separate from the others and hang out by the filter basket, and there is one that was doing that yesterday.
Feeding: they continue to not eat. Prior to this the nine koi (seven large and two medium) were eating three 15g feedings a day no problem. I have been removing the uneaten food and yesterday removed the feeder altogether...I plan on hand feeding small amounts daily to see if there is interest.
Timing of deaths: it is not in the morning when I find the dead koi, but rather in the afternoon or evening. Again, with the two large waterfalls and 10,500gph pump I not believe O2 levels are the problem.
Chemical runoff: I don’t believe there is a reasonable way lawn/ag chemicals could be getting into the pond. I apply a fertilizer two to three times a year, but the last application was months ago and if there was a heavy rain it would have to be flash-flood like and even then the runoff would go *behind* the pond liner. I think this is not the cause/concern.
Pond condition: there is algae and some bio waste in the bottom of the pond in areas, but never enough to cover the cobblestone in the pond...I can see rock everywhere.
So I mentioned above the local koi/pond store. Based on symptoms the recommendation was to add salt (we’ve never added salt), 23lbs for the 3,000gal, and add beneficial bacteria. The folks at the store believe the biology of the pond is off, the waste is not being broken down (causing the foaming), and the salt will help the koi fight secondary issues that are happening from either a bacterial or viral infection, likely from the fish we added. Huge and painful lesson learned. We are very sad. They also indicated alkali condition is okay for the koi, though it will promote algae. So they sold me the proper PH test kit and suggested to get the PH in range, but not worry about 8-9 range and to always test in the morning when PH is lowest.
That was 48 hours ago. Conditions don’t seem to be worsening at this point. The foaming is gone, the water is more clear, and I’m just watching the koi closely and will hand feed to see if they are interested. I was instructed how to look for parasites in the gills and on their bodies too and I don’t believe this is an issue.
I have some pictures of the pond from earlier in the year, but I should take some current pictures and post those so stay tuned.
