Q What is the ideal depth for a koi pond?

A In my experience of over 25 years, 4 to 5 feet is ideal. You need a minimum of 3 feet for koi fish for several reasons. Safety for fish from wading cranes they can not wade in 3 feet of water. Plus the water temperature in shallow ponds fluctuates too much with the changes in ambient temperature. The greater the volume of water, the longer it takes for the temperature to change. Warm water or fluctuating temperatures are unhealthy for fish.

Q What is the ideal size for a pond?

A The ideal size would be determined by the size of your yard. Its size should be proportional to the size of the yard. Also, the larger the pond, the greater the maintenance.

Q What is your opinion on using a liner to construct a pond rather than using a hard molded or concrete one.

A My recommendation is and always has been to use concrete. However, if you are on a tight budget or do not plan on living there for an extended period time, a liner would be recommended. In this case, you would have to add a thin layer of mortar between the liner and soil to prevent tree roots, ground squirrels, rats, mice, gophers or chipmunks from compromising the liner. The hard molded, preformed plastic ponds become brittle from the sun’s UV rays in just a couple of years. No good!

Q What type of pond filter do you recommend?

A That cannot be answered simply because many factors are involved. Do you have an existing pond with a submersible pump or above-ground pump? What’s the volume of the pond? Do you have fish, and if so, how many? What size plumbing pipe is being used? This is so involved, I have devoted an entire chapter in my construction manual to the subject. I have an 8000 gallon pond with above-ground pump and I use a pressurized biological bead filter. It takes 2 minutes to back flush with the turn of a handle and keeps my pond crystal clear.

Q I have tons of algae hanging from the rocks in my falls and growing in clumps in my hand. What can I do to get rid of it?

A When the first Polynesians settled in Hawaii between 300 and 600 AD, they were probably very annoyed by the aggressive, wild, pervasive taro plant, just like you are your algae. They tried to chop it down, burn it, stomp it, but to no avail. It just came back, so they eat it, and still do to this day. In fact, it’s a staple like peanut butter is to some Americans. Just kidding! However, if you told me it was watercress I would suggest eating it. Many pond stores will try to sell you a very expensive algaecide to solve your problem, but all you need to do is increase the salt content of your water. Some experts recommend one pound of rock salt to every 100 gallons of water. This will not hurt your fish; in fact, it will help to produce a healthy shine coat. However, it will harm most of your plants if you apply that dose all at once. Plus the dead and decaying algae will deplete the oxygen and this will harm your fish. Apply it slowly over a week or two, and be patient. It takes longer to kill it this way, but your fish will appreciate it! This topic is also a chapter in my construction manual.

Q Should I keep salt in my pond on a regular basis?

A If you maintain a specific gravity of 1.000, your fish will be less susceptible to ulcer and fin rot. And you will keep the algae from getting out of control.

Q I am considering building a waterfall between my house and my neighbor’s against the fence. Will the sound of the falls annoy them if I let it run 24 hours a day?

A The sound generated by a waterfall is called white noise, which is very relaxing and soothing, not annoying. I have several hundred clients who leave their falls running 24/7 and none have ever had a neighbor complain. In fact, they all appreciate the fact that they did not have to spend the money to enjoy the sound.

Q How many koi fish can I put in my pond?

A The amount could range from 150 to 250 gallons per fish. If you are starting out with small 6″ to 8″ long koi, they can reach 2 feet in three years, depending on how much food and how often you feed them. They could even grow to over 3 feet long! The overcrowding of fish produces stress and a lot of waste material. It can reduce the health of the fish and result in various diseases. Also, a less crowded pond is more pleasant to look at.

Q Do I really need a filter in my pond?

A Not in every case. If your pond is small and you have any guppies or mosquito fish and adequate water plants covering 1/3 to