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I’m new here but Heres my pond I’ve been working on, I’d like some advice on filtration (if I have enough or should change something) and how to keep my koi/ goldfish happy/healthy, and what is my max fish load? It’s about
9173B60B-5AA1-49B8-BB0F-5FBCED380308.jpeg
1600 gallon pond with 2 small koi and about 13 Shubunkin/ comets. It’s 4ft at its deep end. 11’x10’. I have a 4200gph pump with inline UV light and a media filter, in the spillway I have bioballs and aquatic plants growing. Thanks
 

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Welcome @Jimbobpond123 !

I'd say you're already at your maximum fish load. Koi grow big and fast and fish love to make more fish!
Ok, would you say 1000 gallon for first koi and 500 gallon for every koi after? Or like some websites I saw 250 gallons for each koi, or 500 gallon for each koi or 1in per 10gallon or what exactly is the standard here. I see people with koi in 500gallon garden ponds and people say that’s fine but I see 2500 gallon ponds with 5 koi and get ripped apart. I’m just kinda lost with koi to water ratio. And if you say it’s mostly in the filtering. Is my filter set up capable of sustaining 2 koi or? I hear a lot of opinions that are drastically different.
 
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The opinions do vary dramatically, you're right. It's a tough formula to put on paper, because so much of what people will quote you comes from the aquarium world - like 10 gallons for every inch of fish. The problem is 14 one-inch goldfish are no where near the biomass of one 14 inch koi. I'd put 28 goldfish in a 500 gallon pond, but I wouldn't put 2 14 inch koi in the same pond. Mainly because at 14 inches, a koi may be only half grown. So sure, you could put a dozen tiny koi in your pond and be fine... for a while. The problems start 5 or 6 years down the road. That's when people show up here and say "I don't understand... everything has been FINE up until now..."

In my personal, non-scientific opinion the 1000 gallon minimum for the first koi is a good start and a couple hundred gallons for each additional koi after that. Calculate what that comes out to and then plan for less. No one benefits from overcrowding. The problem though is we all know we SHOULDN'T get another fish and we do it anyway!

And yes, filtration plays a big role, but the best filtration in the world will not be enough at some point. And how much work do you want to put into maintaining your filtration? A well balanced pond requires very little work on your part. A koi pond with heavy duty filtration is much more labor intensive.

By the way, if your measurements are right, your pond is more like 2400 gallons (I used a 3 foot average depth).
 
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Thank you for your time and input on this, it’s appreciated. the majority of the pond is 3ft deep with the lowest level from 12-16in deep I did separate dimensions for each step and added all together. Subtracting a hundred or so for rocks/ substrate. But I’ve had a couple goldfish ponds before this roughly 400-800 gallons. I tried to make this pond as deep and large as I possible could, as you see from the picture my patio kinda limited me, and from a lot of what ive read they said 1000 gallons for first koi and 250 for each after. I was hoping 1250 would be enough for 2 and the other 350 or so would be enough for the other goldfish. I could easy be off a hundred or two gallons it’s not a perfect square making specific number kinda difficult. I’m not a pond pro or expert by no means and am open to suggestions like you said it can be complicated I just see a lot of blanket comments on websites that leave open for speculation. Koi I understand are a different animal than goldfish which is why I tried to build this one for 2 koi. The koi I got at petco, they aren’t as quality of koi as one from a Japanese wholesaler lol which I heard may possibly top out at 16-20in? Idk So in all can my hole in the ground support my 2 koi?
 
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And my filtration is fairly self sufficient. Starting at a 4200 gph pump to an in-line UV light out to a filter media canister, cleaned every few days, up to my spillway where I keep water hyacinths, bioballs, other bio filter media’s, out the waterfall falling roughly 3ft for max oxygen input. I have a variety of other aquatic/ semi aquatic plants around to. I hoped the plants would kinda make up for the uv light killing off some bacteria. its just an idea I tried with this pond. Am I missing anything? Thanks
 
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The opinions do vary dramatically, you're right. It's a tough formula to put on paper, because so much of what people will quote you comes from the aquarium world - like 10 gallons for every inch of fish. The problem is 14 one-inch goldfish are no where near the biomass of one 14 inch koi. I'd put 28 goldfish in a 500 gallon pond, but I wouldn't put 2 14 inch koi in the same pond. Mainly because at 14 inches, a koi may be only half grown. So sure, you could put a dozen tiny koi in your pond and be fine... for a while. The problems start 5 or 6 years down the road. That's when people show up here and say "I don't understand... everything has been FINE up until now..."

In my personal, non-scientific opinion the 1000 gallon minimum for the first koi is a good start and a couple hundred gallons for each additional koi after that. Calculate what that comes out to and then plan for less. No one benefits from overcrowding. The problem though is we all know we SHOULDN'T get another fish and we do it anyway!

And yes, filtration plays a big role, but the best filtration in the world will not be enough at some point. And how much work do you want to put into maintaining your filtration? A well balanced pond requires very little work on your part. A koi pond with heavy duty filtration is much more labor intensive.

By the way, if your measurements are right, your pond is more like 2400 gallons (I used a 3 foot average depth).
^^
 

addy1

water gardener / gold fish and shubunkins
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Welcome to our group of pond lovers.

Very pretty pond!

I have only shubunkins/goldfish.

I would not add another fish, they will lay eggs, some of those eggs will survive, you will end up with babies. I have heard that koi lay lots of eggs. I tend not to feed once they start chasing so they eat most of the eggs.

My pond is so full of plants I tend to not feed at all, except now and then as a treat.
 
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To add to the confusion even further, I ran across an article recently that suggested you calculate how many fish your pond can hold based on the surface area of the pond, which makes some kind of sense as well, but it seems like it's still missing the whole picture. My basic conclusion has always been that no one really knows for sure. But I think you're fine. The only way to know for sure will be time of course, but that's true for all of our ponds. It's just always best to start with less than you think your max will be to allow for growth, both in size and numbers.
 
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I have a 3000 gallon pond with an excellent bio filter system, while the water temperature was warm, my water quality stayed good. So I added more fish and had a large spawn the first year. I only say I have a excellent bio-filtration is because I had about four times as many fish as I should have..... everything was great until the temperature dropped and the plants and bacteria died off my pond crashed big time...... I lost all but two fish. So now I have 8 Koi, four of them very large, and when the others get larger I will probably re-home a couple more. It’s hard to not get fish fever when you first start, but less is better especially if you are going to have Koi
 

cas

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Here is a link that explains the size of the fish and the ammonia it produces.

1 SSA (specific surface area) will convert 1 mg of Ammonia per day.
SSA is all the inside pond surfaces and bio filter.
 
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@cas - I've never seen that before. Good information! It really illustrates how much the amount of waste produced by a koi starts to climb rapidly as they get up into the 20 inches plus range.
 

cas

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Also, not all koi get as large as some.
I have 3 koi. The koi that is 13 years old is about 12". Of the two koi that are 10 years old, one is 12" and the other is 8".
However, I have seen koi that are only a couple of years old and they are approaching 2 feet.

My recommendation is to keep an eye on the amount of the fish you have and their size and rehome some when the SSA of your pond can't support them.
 
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I would say your koi are definitely on the small side. Ours, at 7 & 8 years old were mostly over 18 inches. We had a couple that were over two feet. Only one of ours stayed around 12 inches long. It would be great if someone could work on breeding koi that would stay small. People love them for all the different colors and patterns, but the size definitely becomes and issue in smaller ponds.

But I am now #teamshubby with @addy1 ! They are just as pretty and fun to watch and do get to a nice size that works well in every pond.
 
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