Building a koipond.
Most important when building a koipond is the design before the first start.
Start digging before everything is well looked at and designed will cost you a lot of money!
Bad pond and filter design will cause trouble like fish disease and many then eventually quit the hobby which can be avoided.
Budget, size,shape, filtercapacity, position of bottom drain(s), pumps, uv, positions of return and flow directions, plant filters, waterfalls, skimmers, bypass systems, overflows, everything has an influence on each other when making a design.
Make sure you talk about your plans to koidealers and experienced hobbyists, through a internet forum for instance before starting. it can be done right in several ways and wrong in much more.

A good example of an overview of a decent system was made by waddy (copied from his site)
The filter is not always the best, this depends on the situation but the drain, returns, and such are well situated.
The filter is not always the best, this depends on the situation but the drain, returns, and such are well situated.
A remark on the bottom drawing, the bottom should not decline this steep, this has been drawn to show where the dirt goes. only a small decline is sufficient.
Some pointers:
-your budget determines what you can build, so first determine what you are willing to spend.
the filter is the heart of the system and really determines whether you will enjoy your koihobby or not, never ever go cheap on it. buy and install a good filter the right way and the hobby is for 70% guaranteed to work out well.
-beadfilters are not used by the breaders in Japan, must be a good reason that they all go for the chamber filters....
-be aware that you need tapwater (or good quality water supply) and let cubic meters of waste water go to the suwage.
-make an overflow to the suwage to prevent the garden to go blank after rainfall.
-ideally is an automatic water top up system.
-if you have the means, pond heating is perfect for koi in the early spring and fall for the condition of the koi, heating in summer will cause gigantic growth.
-isolation, also without heating, it will make a big difference in keeping the water temperature more stable.
- placement of the (aerated) bottom drain is crucial, the air bubbles on the surface can prevent the food to fall in the skimmer, but also floating dirt.
-think about replacing sliding valves, its not if but when they will brake down and need to be replaced every few years.
-make sure you can take your UV out when you dont need it, so make a bypass that does not stop the water flow.
-the plant filter and waterfalls need to be able to be turned of in winter time because the water temperature wil drop to fast.
-use only long corners in piping, 90 degrees turns can decrease the water displacement of a pump by 50%.
Some pointers:
-your budget determines what you can build, so first determine what you are willing to spend.
the filter is the heart of the system and really determines whether you will enjoy your koihobby or not, never ever go cheap on it. buy and install a good filter the right way and the hobby is for 70% guaranteed to work out well.
-beadfilters are not used by the breaders in Japan, must be a good reason that they all go for the chamber filters....
-be aware that you need tapwater (or good quality water supply) and let cubic meters of waste water go to the suwage.
-make an overflow to the suwage to prevent the garden to go blank after rainfall.
-ideally is an automatic water top up system.
-if you have the means, pond heating is perfect for koi in the early spring and fall for the condition of the koi, heating in summer will cause gigantic growth.
-isolation, also without heating, it will make a big difference in keeping the water temperature more stable.
- placement of the (aerated) bottom drain is crucial, the air bubbles on the surface can prevent the food to fall in the skimmer, but also floating dirt.
-think about replacing sliding valves, its not if but when they will brake down and need to be replaced every few years.
-make sure you can take your UV out when you dont need it, so make a bypass that does not stop the water flow.
-the plant filter and waterfalls need to be able to be turned of in winter time because the water temperature wil drop to fast.
-use only long corners in piping, 90 degrees turns can decrease the water displacement of a pump by 50%.