New pond help

[Jparrish989]

Hello, I am new to freshwater ponds but have kept reef tanks for many years

Long story short I dug out and built up a CMU pond that measures 6x10x4 with a bottom drain. It is on a optima 2000 bio mechanical with a 40 watt uv in line pumping at 6100 gal/hr. Most of the water returns through two water falls that are about 18” above the water line. It is filled with San Diego municipal tap water which I believe comes from the Sweetwater water district. After filling, I treated the water with ultimate water conditioner by pond solutions and gel bacterial inoculate. I then waited a week and tested. The permitted are all ideal with GH being 180. I asked around and nobody seemed to think the hard water was an issue. I added three water Lillies and they all have opened and closed everyday with new leaves coming to the surface after three or four days.

I then proceeded to go to the store with the intention of buying some tester fish to see how the fish did. After talking to the main pond guy and telling him the parameters I proceeded to just go for it and bought a few 5” koi. They proceeded to die after an hour and I am perplexed to what might have gone wrong. Any help so I don’t make the same mistake going forward would be appreciated.

 

[CometKeith]

Hi. Welcome to GPF. I'm sorry about your fish. Obviously there was no beneficial bacterial built up in your pond but I would be shocked that an ammonia spike would kill your fish so quickly. Have you tested the water since then? Also I'm wondering how your ph is and if the CMU is making it very high. Also thinking somehow your fish went into shock but don't know what caused it. Any chemicals leeching into the water? Definitely try again with a couple small goldfish and see how they do. They will be less susceptible to ph and won't produce much waste.

 

[Jparrish989]

Thank you for the quick response. I am using api 5 in 1 test strips. According to the strip, I am in between 7.5-8.0. When the fish died, less then 3 hours after putting them in, I assumed I missed something so I tested again and everything was perfect with the only thing being a very high GH.

As far as the CMU, it is watched, sealed then primed. Then layered with 6 layers of herco black as thick as I could apply it. I don’t think anything is leeching in. But it is always a possibility. Is there anyway to test for other contaminants? I did seal the bottom with roofing tar but it isn’t suppose to leech and everything I researched said it was aquatic safe.

 

[CometKeith]

Thank you for the quick response. I am using api 5 in 1 test strips. According to the strip, I am in between 7.5-8.0. When the fish died, less then 3 hours after putting them in, I assumed I missed something so I tested again and everything was perfect with the only thing being a very high GH.

As far as the CMU, it is watched, sealed then primed. Then layered with 6 layers of herco black as thick as I could apply it. I don’t think anything is leeching in. But it is always a possibility. Is there anyway to test for other contaminants? I did seal the bottom with roofing tar but it isn’t suppose to leech and everything I researched said it was aquatic safe.

Hmmm... How did the water temp compare to where they came from to your pond water? Was it fairly close? Large differences in temp can put fish into shock. Also did you float the fish first in their bags and follow proper procedure for introducing new fish? I'm thinking it's not an issue with dissolved O2 because you have so much water movement, but that could always be an issue. Low O2 can quickly kill fish. The larger the fish the more susceptible they are to low O2. Did they try jumping out? I'm thinking it's definitely not an ammonia, nitrite, or nitrate issue even though you didn't cycle the pond first because it wouldn't kill them so quickly. I don't agree with the guy in the store. You should have started out with some really small fish to cycle the pond before buying the 5" Koi. I hate to say this but sometimes the first few fish are the sacrificial lambs and they die so you can have a healthy pond for your fish for many years in the future. I would try putting in two 2" goldfish. and watch them for a few weeks before doing anything else. If they die then it's definitely a chemical in the building products you are using causing the problem. A quick fix would be to buy epdm and line the inside with it. I would suggest any material you use you should buy from a pond supplier. I'm in construction, but I never trust materials for my pond that didn't come from an aquatic supplier. I hope this helps. btw your pond is beautiful! I'm sure in no time it will be up and running with nice fish!

 

[Lisak1]

Good advice from @CometKeith . I would also suspect the difference between the water they came from and the pond water was the culprit since they all died so fast.

How many gallons is your pond? Is it big enough for koi? I know you said these were only 5", but koi grow fast and furious. Unfortunately lots of "professionals" sell koi to people who don't have the ability to provide a healthy environment over the long term so it's always a question I throw out there!

You may also find that water lilies struggle in your pond. They aren't fond of a lot of splashing on the pads and from the photos it doesn't appear that you can get them far enough away from the waterfalls to prevent that.

Beautiful pond by the way!