Temp is dropping and goldfish are dying one by one

[Jkm]

I have a new pond, round-ish, about 35’ diameter, 5’ deep at the drain, with sloping sides so probably an average depth of 3’. I suspect it holds at least 18,000 gallons. All well water, very good quality. PH consistently 7.6, and so far the ammonia, nitrite, and nitrate all read zero (using the API liquid test kits).

The pond was dug and lined with pond liner in August 2018. It has a very large filter, skimmer, waterfall, and sub-surface returns. Full sun, no plants yet.

My goldfish consisted of two large ones (8”-9”) that I’ve had since they were small, living in a 150 gallon horse water tank, in the barn with a deicer each winter and moved outside each summer. Last year the two original goldfish spawned and 12 babies made it to 2”-3”, so it was time they had a real pond.

All was well until the last few weeks. Two weeks ago (end of October) the water was turning green so I treated it with AlgaeFix and Accu-Clear, with lots of aeration. The water went back to being crystal clear but I’m afraid I might have overdosed the pond because ever since I’ve been losing fish one by one. Last night I lost my big old male, after he spent days lying on the shallow shelves and being very lethargic. Not gasping for air but not at all well. Up until yesterday I was feeding them a tablespoonful of wheat germ food every three days, and they would eat it very slowly. As of now those that are still well are not eating any more.

Now the water temp at the bottom is 41 degrees, the surface temp is 45 degrees, and we are getting ready to winterize the pump and filter system and turn them off. I have a 1500W floating deicer in a shallow area, next to a separate aerator that’s lying at about 3’ deep, which should keep a decent hole in the ice without messing up the cold puddle on the bottom.

Is there anything I can do at this late date to somehow fix what I did to the water with the AlgaeFix? Or to protect my remaining goldfish (1 large female and 6 offspring)? Would filter bags of charcoal in the skimmer help?

I am brand new to having a real pond, and it seems like the more I do to make it wonderful, the more problems I cause.

 

[poconojoe]

A partial water change. Maybe 1/3 of the water changed. Maybe in a week or so, do it again. Don't remove or clean you filtration after the water change. Give the water a chance to repopulate the good bacteria.

You will find that the consensus here will agree that adding any chemicals to clear up your water is a no-no. Goldfish are very hardy fish, so I'll bet those chemicals are what is doing them in.
The only thing I add is dechlorinizer since I have central water that is treated.
The best thing to clear up green algae water is to introduce plants, and the more plants the better. The plants thrive on all that algae. It's a complete natural cycle. You need this cycle in order to have a healthy pond environment. The fish produce waste which creates algae and the plants absorb the algae. The larger the fish load, the more algae.
That being said, having clear water is a human thing. The fish don't care if the water isn't sparkling clear.
Keep us posted on how you are making out.

 

[poconojoe]

Also, when it comes to ponds in general, things don't happen overnight. What I mean is, for example, when trying to achieve clear water by adding plant life, it takes time for the cycle to complete. It's all about patience with ponding.
You are best to read and read throughout these forums since you are new to ponding. Especially the subject of filtration. Lots of things come into play. Such as type of filtration, size, beneficial bacteria, etc. There's a ton of knowledge here. And don't get discouraged. Once your pond is up and running with the natural cycle working, you can sit back and enjoy! You really don't need to do much once it's all set up correctly.

 

[Jkm]

Thank you. I was afraid you would say water change... that’s a lot of water, and my concern is that the temps are so low now. Is it safe to do such a big water change (or two) when the water should be starting to establish thermoclines? Would it help this first winter to put a sinking livestock tank deicer down at the bottom? In the stock tank they always had one to keep the water at about 41 degrees, because the water tank was above ground in the barn, but if I had not used chemicals to make the pond water and fish pretty, they should survive the winter without it, yes?

And would a small amount of calcium bentonite help to remove any toxins? Will the toxins eventually degrade on their own?

I’ve been reading voraciously about ponds since I began this project, and there is so much yet to learn (and to sort out what’s useful from what’s not).

Thank you for helping me so quickly.

 

[Mmathis]

@Jkm Hello and welcome! I’m sorry that you’re having this problem - it’s bad enough to have problems with a pond, but I think it’s worse when it’s a new pond and you’re still in the learning process. The best way to manage a pond is to do as little as possible — patience! Green water is normal and will eventually correct itself. Maybe, do a few water changes....? But after that, let Mother Nature do her job.

What kind of filtration do you have? You mentioned a bottom drain.

Tell us, where do you live — what climate zone? Where I live (Louisiana) the pond temps don’t normally get that low (if at all) until Jan/Feb, so I have no concept of what water temps. are like in other areas.

With a pond that large, and so few fish, I wouldn’t expect to see much of a change in your water parameters. Is there a chance that any lawn chemicals or pesticides could have gotten into the water?

Please post some pictures of your pond for us.

 

[Jkm]

Hi, I took pictures this morning. I’m in north Idaho, near Spokane, WA and Coeur d’Alene, ID. I think it’s zone 5 or 6. It was 28 degrees when I got up this morning. The pond temps is 39 degrees both at the drain and at the surface.



I lost another 4 3” fish last night. Now I have one 9” (one of my two originals, the female), one 3”, and one small feeder. You can see them in the photos.

The pond is unfinished; it was dug in August and filled in September, and the fish went in then.

Now I wonder if I should rescue the last three fish and put them back in the barn for the winter. In my barn I have five horse stalls, each with its own 100 gallon Rubbermaid stock tank for water. The stock tanks have heater/deicers and the temp in each of them is 50 degrees.

Then what do I do with the pond over the winter to get it ready for spring?

 

[Jkm]

I thought I had it all figured out, and have researched ponds all over the internet since long before the digging began, and now I seem to know nothing. I’ve got several books on goldfish ponds, lots of printed internet articles, and there still seems to be a lot of information missing. Maybe I’m overthinking this; clearly I expected it to happen a lot more quickly than it did. The algaecide seemed to work so well (until my fish began to slowly die). Last summer I had two dozen bright, active, colorful goldfish enjoying their new vastly expanded surroundings; the water was bright and clear and the fish were pretty and it was wonderful until the water began to turn green. I had no idea that the green water might not be a catastrophe. Until very recently I’d never heard of calcium bentonite clay and that it could be a good thing in my pond, or that chemicals labeled “fish safe” might not be.

Now I’m back to square one - but at least the pond is dug and lined and plumbed. Ready to plant and start again in the spring, and maybe make better decisions. I look forward to researching a lot on this site.

 

[poconojoe]

Before you lose more, moving the fish to the barn seems like a good idea.
In the spring you can take your time and figure out what went wrong. Maybe empty the pond and start over. This way you know there aren't any harmful chemicals in there. Normally starting over like that would not be a good suggestion. But since your pond is new, you won't really be losing any beneficial bacteria.
I would suggest you get one of those economical water gallon counters that attach to the end of your hose. This way, when refilling, you know exactly how many gallons your pond holds. I bought one on Amazon a few years back. I think it was about $15. Well Worth it.

 

[Jkm]

Never heard of that - great idea!

My husband and I are going to go move the remaining fish into the barn now, and start over in the spring. He can play with the plumbing in the winter all he likes once the fish aren’t there any more.

Update 30 minutes later:

The big female was lying upright on the bottom, stone cold dead. The 3” fish was barely alive, and the 1-1/2” feeder was doing pretty well. Both in the stock tank in the barn now. The little one seems fine; the bigger one began moving right away, but looks like it’s sluffing off a coat of scales, if that makes sense. I am resigned now to losing them both - that will make a complete loss of fish.

Now I need to study up for starting over in the spring.

 

[poconojoe]

I think someone asked this already...but is it possible some fertilizer or other run-off made its way into the pond? Maybe from an uphill neighbors property during a severe rain storm?
What about the pond liner? What was used as a liner? Was any glue or adhesive used?

 

[Jkm]

No possibility of fertilizers or chemicals other than those I added; pond liner is an EDPM pond liner purchased from a pond supplies store online. No glues.

One of the many stupid things I did earlier was to make a “collar” for the drain - to keep the little fish out of it - I made the collar out of galvanized steel 1/4” hardware cloth. It worked well, but not long afterwards the fish began acting unwell. I discovered galvanized steel (zinc) was toxic and pulled it out, stopped using the drain so I wouldn’t suck up little fish, and treated the pond with Pond StressCoat to de-toxify the heavy metals. They seemed to get better after that.

I didn’t keep a good pond calendar of what I did when, so it’s a little hard to recall all the stupid “good ideas” I had.

When it was still warm I fed them twice a day and now I know that’s wrong. When I learned that I was over feeding them I cut way back, and they kept the liner very clean and didn’t starve to death. When it began to get cold (50) I began feeding them every three days with wheat-germ based food, which they would eat slowly, and I stopped feeding them at 43 degrees - maybe a week ago or two. By this time there were only a dozen and they’d begun dying one by one.

 

[Tula]

I'm amazed you caught the fish in a pond that size, well done Can you take a picture of the ones in the stock tank with the scales sloughing off? We might be able to better help you if we could see the fish.

Don't beat yourself up, it's a steep learning curve to achieve a well balanced pond.....you'll get there and now have all winter to prepare for our favorite time of year - SPRING !

 

[Mmathis]

@Jkm How is your filtration set up? Do you have a pump and filter? What about any extra aeration like from an air pump or waterfall?

Do you test your water? If not, maybe get a liquid test kit (API is what most of us use) and start testing for pH, ammonia, nitrites, nitrates, KH, and GH. And if you can, a test for oxygen is available and helpful. Please get back with us with those number values (not “OK” or “normal”), and we’ll see if we can help you figure this out.

 

[Jkm]

I have an Ultima II biomechanical filter (I think it’s a 20,000) with an ArtesianPro big pump (I don’t have the specs), a Savio Skimmerfilter, and an Aquadyne Rhino II bottom drain. My husband ordered all the equipment and did all the work, so I’m fuzzy on the specs, but I think he overbuilt it just in case.

The bottom drain has a central aerator attached to a linear air compressor. The big filter, pump, and air compressor are in an insulated shed. There are accommodations for UV in both the filter and the skimmer, but I’m not using UV (it’s expensive and I’m not convinced it’s a good idea).

The filter draws water in through the skimmer or the drain - both are on valves and can be opened and closed separately. The outflow from the filter goes to both an unfinished waterfall and a submerged outflow pipe that’s 2’ below the surface and pointed up so it flooms to the center of the pond. Both outflows are on separate valves, also. The aeration from the bottom drain can be turned on and off separately from everything else.

I test the water regularly, same as my aquariums, with the liquid API kits. The pond water has always been zero ammonia/nitrite/nitrate, pH 7.6, and dissolved O2 about 6-8 ppm.

The pond setup should be good. I plan on planting it heavily next spring, and my husband will build a very tall waterfall.

What I haven’t figured out is whether the water should run all winter - from the skimmer through the filter and back out through the submerged outflow pipe, or would that keep the temps too stirred up? Next winter, when I hope to have fish in it again, do I shut everything down except for the shallow extra aerator and the floating deicer at the shallow end?

If I can get it properly set up, I’d really like it to self-maintain and establish its own ecosystem. I think that’s how it’s supposed to work eventually, right? But I don’t know what to do for winter for the fish, and I’m nervous about putting new fish in next spring/summer.

 

[Jkm]

This is the 3" fish that's sluffing its scales.
Both big fish did that before they died, also.
What could it be?