The photo above is that of a Koi (Japanese carp). This one is a Goromo - one of the many different varieties of Koi . One of my first and certainly not my last.

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Tuesday, November 2, 2010

Koi Pond Bottom Drains

A key feature of a well-designed Koi pond are drain pipe(s), also known as the Bottom drain(s),  linking the bottom of the pond to the inlet of the filter system.   In my current 13-ton pond, water enters the filter through two 4-inch diameter (100 mm diameter) pipes. Two other lead-in pipes (75 mm diameter) pull water from my water garden pond and also from the bottom drain of my water feature. See my earlier post on filter design. 

Location of bottom drains.

The bottom drains should be near the geometric center(s) of the pond, and evenly spaced out if you have more than one bottom drains. A good pond design will be to slope the bottom of pond towards the bottom drains. This allows any physical dirt at the bottom of the pond to be pulled  towards the drains by gravity.

The bottom drains should draw pond water into the filter. Each bottom drain should have its own pipe into the filter chamber. It does not make sense to have 2 or more bottom drains daisy-chained via a single or shared pipe (water will only flow in through the pipe with the least resistance and the other drains will be mostly ineffective). Typical size of pipe is with 75 to 100 mm diameter.

Importance of having a good drain cover.

Drain covers can ranged from simple DYI covers to commercially-built drain covers. My current pond uses a simple mesh, force-fitted onto the top of the drain.

A Koi should not easily dislodge the cover. I have lost a few Koi in my first 2 ponds after the cover was dislodged and a Koi found their way into the filter.

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