Koi Maintenance and Care Pumps and Skimmers

You next have to estimate the volume of your pond in cubic feet using equations for the shape or by drawing top and side views of your pond to scale on graph paper and counting the squares. Each cubic foot equals 7.5 gallons of water so find out how many total gallons of water your pond and filter system will hold. Remember, you will need to keep the water level 10 inches from the top of the rocks, bricks or what ever material you have surrounding the edge of the pond to keep critters out and fish in the pond. Koi can jump higher than you think and many have jumped out of a pond when startled. Once you know the gallonage of your pond, then select a pump that will turn over that amount of gallons within 2 hours. Less time is better.

So if you have a 4000 gallon pond, add 25% for the water in the rest of the system and filters for a total of 5000 gallons and select a pump that can pump at least 2500 gallons per hour or dividing by 60 minutes gives about 42 gallons per minute. It is much, much better to use two pumps for your pond for the following reasons. First, you can plumb your system so if one pump goes out you can switch the total filter system to the other pump. Second, when you go to treat your pond with chemicals for parasites or bacteria, you will need two pumps to run the pond and the separate filter system. A 1/6 Hp pump will deliver 42 gpm and will cost about $350 to purchase and about $15-20 per month to run depending on your electricity rates.

High efficiency Hp Lim brand Wave pumps are available for about the same purchase cost and run for about $35 per month electricity and pump 80-100 gpm depending on the head. What is head? Head is the distance in vertical feet the pump must raise the water from the pump to wherever it is going, say to your filter. For above ground tank filters this is probably around 6 feet. But there are losses in the piping and bends due to friction so you may have another 5 feet of head due to these losses.

So when you look at a pump curve, you see a curved line showing less pump flow for higher heads because it takes more work for the pump to push the water higher. Look at the point on the curve with a head of about 10-12 feet to determine your true water flow. Always use 2 inch diameter PVC piping into your pump and from your pump to the filter to reduce head loss. Always use a minimum of schedule 40 PVC pipe or ABS that is the black plastic piping for drains. Minimize the use of sharp 90 degree elbows by using two 45 degrees together, ABS generous 90 degree sweeps or PVC flex pipe. PVC flex pipe must be painted to protect it from the sun’s UV. Koi pond pumps are not the 1.5 – 2 Hp monster pumps used for swimming pools.

Koi pond pumps are good at pushing water but not good at sucking water so koi pond pumps should be placed in a water tight vault below the water line of the pond or pre-filter to always maintain positive water head pressure on the inlet. Pumps will suck down a pre-filter 1-3 inches before equilibrium is obtained on incoming water from the pond and outgoing water from the pump. If you must place a koi pump above the water line of the source, install a flow directional gate or check valve to keep water in the pipe going to the pump when the electricity goes off. This will keep the pump primed with water and avoid the pump sucking air when the power returns.

This check valve should be below water line. This type of valve is also important if you forgot to design a bottom drain into your pond and you are bringing the water up and over the edge of the pond to the pump. You must keep water in the line going into the pump when the power goes off to have the pump work properly when the power comes back on. Pumps don’t pump air very well. Swimming pool pumps resolve this with high suction, high Hp pump design. In-pond submersible pumps like Cal or Rio pumps can work for koi ponds. However, be forewarned, I have had Cal pumps leak oil and also leak small amounts of electricity into the water which will damage the koi. But I use these pumps to move water from one place to another and am always handling the pump. If placed into the pond and left alone, this may take years or may never happen with Cal pumps.

 Rio pumps are ceramic without oil so that issue is resolved but they will destroy themselves if run while dry without water present. High efficiency koi pumps are usually available in 1/15, 1/6, and 1/3 Hp models. Several manufacturers are available with good pumps but I can recommend the W. Lim pumps series called Wave pumps or Dragon pumps for efficient pumps as the ones I chose for maximum efficiency and water flow.

Posted in: Fish Ornamental