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Do Koi Ponds Need Water Changes?

Water Change in Koi Ponds San Diego, CA

While a koi pond is a wonderful addition to a home, it also requires upkeep. Beyond keeping your koi fed and healthy and having the right koi pond supplies on hand, you need to know that good water quality is necessary to their health and happiness. One of the best ways to maintain your koi pond is changing out the water. This article will detail the water changing process and mention some major factors involved therein.

Why Does the Water Need Changing?

Failing to change out the water allows ammonia and nitrites to saturate the water to troubling levels. A lot of people have the misconception that just adding water to displace evaporated water is the same as a water change, but this isn’t the case. Whenever water evaporates from any non-circulating body of water, pollutants remain behind. While the pond’s good bacteria are still able to do their work, the chemicals involved in the nitrogen cycle can sometimes leave the bacteria with too much to do, leading to diminishing quality. Changing water out in portions can prevent this problem from manifesting.

How Do I Change My Pond’s Water?

Stick to a weekly schedule of cycling out 10-20 percent of the water in the late spring to early fall, then once a month for the rest of the year. Exchange it for an equivalent amount of fresh, dechlorinated water. Simply check the volume of water your particular pond can hold, drain the pond by this percentage, using any sort of pump or vacuum, then refill it back with fresh water via a hose or whatever else you usually use for filling your pond, adding a dechlorinator when you do so. Consider emptying the sucking implement’s contents into a clean trash can, ideally one with volume amounts marked along various heights to more accurately replace the water. You can also use this canister as a dechlorination stage for the fresh water. Furthermore, you should change the water in a way that doesn’t stress your koi. Always go from cold water to warm water, never warm to cold.

What Other Considerations Go into Maintaining Koi Ponds?

To maintain the pond’s quality, it’s a good idea to have plenty of chlorine remover like Prime:


Chlorine isn’t only toxic to fish but also to the good bacteria. You should look for a chlorine remover that can deal with chloramines—many municipalities are fond of using chloramines when chlorine is involved. Changing the pond’s water also helps you manage the pheromone levels. An excess of pheromones can inhibit koi development. Both pheromones and chemical pollution can be kept in check with a regular water change.

What if I Notice Toxic Levels of Ammonia, Nitrites, or Nitrates?

If you detect high levels of ammonia, nitrites, or nitrates, exchange 30 to 50 percent of the pond’s water to dilute the pollutants to levels your fish can manage, reduce feeding, and add bacteria. If you notice your koi are becoming weak or sick from flagging water quality, consider daily changes of 20 to 30 percent for a few days.

In addition to making water changes, there are a variety of supplies you need to have on hand to properly care for your pond. From koi pond filters to beneficial bacteria, Aquatic Warehouse has everything you need. Stop by our store in Kearny Mesa, check out the products on our website, or give one of our experts a call today at 858-467-9297.


Contact Information

  • Address: 5466 Complex Street Suite 204
    San Diego, CA 92123
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