diferentes tipos de estanques

Top 5 mistakes when building a koi pond

Top 5 mistakes when building a koi pond

“If I had known before …” is a phrase which we hear very often in Koi Hacienda when our clients consult us because of problems they have in their pond.

With the article Top 5 mistakes when building a koi pond we want to give the possibility of learning from the mistakes of others.

1. Decorative pond or koi pond?

There are decorative garden ponds and there are koi ponds.

Two absolute different issues. 

diferentes tipos de estanques

Decorative garden pond and koi pond (more purist => easier to keep water clear)

Of course you can have koi in a decorative pond, but – as a rule – at some point begin the problems: algae, muddy water, sick koi …

If you want a koi pond, you should decide to build a real koi pond. With healthy koi, crystal clear water and minimal maintenance to have time to enjoy your koi.

2. Too small

Let’s see: people who have little space available and want to have koi, obviously they have no other choice than building a small pond. But those who have space in their garden and start with a 2m x 2m and 1m deep, would commit a big mistake.

The general rule for healthy koi that can optimally develop would be: 1000 liters (= 1m3) per koi.

This means – according to the example above – that the owner of that pond could only have 4 koi (2m x 2m x 1m = 4m3 = 4000 liters => 4 koi)

Of course at the beginning you can introduce many more, but nature is wise: Koi grow less if there is little space (or overpopulation).

3. Depth

“If I do it deeper, I will not see my koi.”

How many times have we heard that!

Honestly: It’s really silly. If you have a koi pond in good condition, your will see your koi perfectly. 

I think I have already posted enough videos of the koi in Koi Hacienda (if you have not seen them, I leave you some links below) in which you can see the koi perfectly. The main pool at Koi Hacienda has a depth from 2m – 2.70m. And no problem so see them. 

Depth is required to:

A) development of the “torpedo” form of the koi

If the koi have no depth and grow, they will be large, but elongated koi. Not with the typical form of “torpedo”

B) temperature variations

In summer, at the bottom it is cooler. In winter, at the bottom the temperature is more temperate. Koi can look for the temperature they need. With a shallow ponds they do not have this ability to balance their body temperature.

C) algae

Algae fundamentally need two things to grow: food and sunlight. The food is usually food remains of koi food and feces that are at the bottom of the pond. If the bottom of the pond is shallow, the two requirements are given. If the bottom of the pond is deep, less sunlight comes in and more difficult for algae. And if the bottom is clean, none of the requirements are met and algae can not survive in this pond.


agua verde koi

Very green pond due to algae

4. Little by little

Starting with “little by little” is another of the Top 5 mistakes when building a koi pond. 

I fully understand that building a good pond can be an important investment depending on the budget of each home. If this is the case, I advise this person to wait and save instead of starting right now with solutions “little by little” for a simple reason: In the end, you always pay more.

Beginning with the points mentioned above (small and shallow), combined with inexpensive machinery, can provoke stop wanting to have koi because one will spend hours cleaning inappropriate filtration systems, will be frustrated because they do not see their koi due to dirty water and will be discouraged because the koi get sick (or at worst die) because of poor water quality.

Today with internet we can afford a comparison of the same product within seconds. And the “click” to buy and pay with card is very easy. But if you buy your filtration system 75 € cheaper in France who will solve the problems later? Will you call (if you find the phone number somewhere) to France when it breaks and you need a spare part?

Another aspect of “little by little” is the expenses that come later. Example: I buy an economical pump for my filter. But what about the bills of electricity that come to me monthly? Our BlueEco pumps are more expensive, but the manufacturer announces up to 50% of energy savings which can make it profitable within the first year.

bomba filtro

Blue-Eco pump – low energy consumption granted

5. Oxygen

Beginners think that koi only need water to live.

Well, NO.

Here we go with the fifth of the Top 5 mistakes when building a koi pond. 

They are living beings and like all living beings they need oxygen. This oxygen is – in different concentrations – in the water.

The warmer the water, the less oxygen there is.

In most cases, in summer koi need additional oxygen in order to survive. And a cascade of a decorative garden pond is not enough.

If there is no bottom drain with aeration, the oxygen can only be provided later through an external air pump and tubes with oxygen stones introduced into the water. It is not very aesthetic, but at least they serve.


I hope the Top 5 mistakes when building a koi pond will be a useful article for you. And you know: This is a blog, a place to share and exchange opinions. If you want to tell us your experience when building your pond, your comments are welcome.


To discover Koi Hacienda: Virtual Tour 

Main pond in Koi Hacienda: The art to catch a koi

Closer look to the main pond in Koi Hacienda: Giving food

Like that we start the day in Koi Hacienda: Good morning Koi