Koi Pond Filter System

by Mike Casey

This is not a water garden, it is a fish pond. Water gardens are typically shallow and don't require a filtering system.

We built this Koi pond in our back yard during the year 2000. The purpose of this page isn't to talk about our pond but to help other Koi pond owners with their filtering system. But, for those of you interested in the pond. It contains 6,000 gallons of water, is 5' deep with a bottom drain and a skimmer. The patio surrounding it has 12 tons of flagstone.

If you are just starting your Koi pond, the following are pointers which may prevent you from making some of the costly mistakes I made:

  1. Join your local Koi Club.
  2. Order the Aquatic ECO-Systems, Inc. catalog. It is free. Phone 407.886.3939
  3. Use only EDPM liner. DO NOT use a PVC liner.
  4. Your pond must be at least 5 feet deep and slope down to the bottom drain.
  5. You MUST have a bottom drain.
  6. Install both a bottom drain and a skimmer. The best bottom drain I have found is from W. Lim Company.
  7. Install a 3-way valve on the input of the filter system.
    This allows you to blend how much water comes from the bottom drain and the skimmer.
  8. For the health of your Koi contact Dr. Erik Johnson. Buy his book and video tape.
  9. You MUST have a bottom drain!
    If you don't have a bottom drain, how do you plan go remove the fish feces?

The typical open type filtering system, for a Koi pond, is larger than the pond. Since, we didn't have that kind of space we opted for a closed system which we purchased from Fluid Art Technology. After purchasing the system we found that an additional benefit is that a closed system requires less maintenance. It takes us about twenty minutes per week to backflush the system. I highly recommend Fluid Art Technology. Their products are excellent and more importantly their service after the sale is some of the best in the industry.

Those of you who purchased a Fluid Art system before 2001 should update your system by installing the new hydraswirl solids separator inside the Challenger bead filter. Our pond was clear before we upgraded and after the upgrade it is extremely clear. Also we have observed, that the water is much clearer when the pump is run at low speed.

The system we purchased was the Challenger 60 Ultimate System. We made modifications to the system which I will discuss later in this article. The following PDF files are drawings of the system as it is shipped from the factory:

Pond Cleaning Instructions


A note about putting the bio beads inside the Challenger: You will receive more beads than you should use. Do not fill the Challenger to the top with beads. When filled with water you must have a space underneath the beads for the hydraswirl solids separator to swirl the water. On the Challenger 60 we measured the distance from the bottom of the Challenger to the top of the hydraswirl solids separator and found that it was 10 inches. When we loaded the beads we left a 10 inch gap between the top of the beads and the top of the Challenger. Then later, when we filled the Challenger with water, the beads floated to the top and left a 10 inch gap on the bottom.

The Modified Filter System

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All Pages and Images Copyright © September 3, 2001 Caseys' Page Mill, Ltd