Water changes are a crucial part of koi pond maintenance, especially when ammonia or nitrites begin to accumulate. One common cause of this chemical buildup is evaporation. As water evaporates from your closed system (your koi pond), it leaves behind pollutants. While beneficial bacteria work tirelessly to break down harmful substances through the nitrogen cycle, they sometimes need a helping hand. That’s where regular water changes come in, giving them a boost and keeping your pond environment balanced.

Why Koi Pond Water Changes Matter

Poor water quality is one of the leading causes of koi health issues, including disease and even death. Simply topping off your pond to compensate for evaporation isn’t enough—you need to remove pollutants and dissolved compounds by doing partial water changes. Regular water changes help maintain a healthy ecosystem and improve water clarity.

Generally, 10-20% of the pond water should be drained weekly and replaced with fresh water from your tap or well. But before you start, always have Kloubec Koi Farm Water Preparation, our go-to chlorine and chloramine neutralizer, on hand. Chlorine is highly toxic to fish and beneficial bacteria, and many municipalities also use chloramines, which require specific treatment.

The Hidden Benefit: Pheromone Reduction

Did you know that regular water changes also help increase koi growth by reducing pheromones?

What are pheromones in the koi pond?

Pheromones are natural chemicals released by fish that influence the behavior and development of others in the pond. In high-density koi ponds, aggressive pheromones can inhibit growth and weaken disease resistance. By performing regular water changes, you help dilute these chemicals, allowing your koi to thrive.

Avoiding Temperature Shock

Water has a high specific heat, meaning it resists rapid temperature changes. However, sudden fluctuations can be stressful—even deadly—to koi. The best way to introduce fresh water is to add it gradually into the last filtration stage, where it will be pumped into the pond and mixed more evenly. Major water changes should be done cautiously, as sudden shifts in temperature can also disrupt the beneficial bacteria that keep your pond healthy.

Emergency Water Changes for High Ammonia or Nitrite Levels

If you detect dangerously high ammonia, nitrite, or nitrate levels, act fast!

• Perform an immediate water change of at least 1/3 to 1/2 of your total pond volume.
• Follow up with 20-30% daily changes if water quality remains poor.
• Keep in mind that fresh water only dilutes toxins—it doesn’t remove them entirely.

How to Perform a Water Change

1. Drain the fouled pond water. Use a pump, pond vacuum, or siphon hose to remove dirty water. Using a plastic trash can help measure the amount being removed.
2. Prepare fresh water. Fill a container with fresh tap water and treat it with Kloubec Koi Water Preparation to neutralize chlorine and chloramines.
3. Refill gradually. Add the fresh, dechlorinated water directly to the pond or into the last filtration stage to reduce temperature fluctuations.

Many pond owners recycle discarded water by using it to irrigate gardens and lawns.

Pro Tip: Prevent Overfilling Accidents

Invest in an automatic water shut-off valve from your local hardware store to prevent overfilling, which can be deadly if untreated tap water floods the pond. Even the most experienced koi keepers can forget to turn off a running hose—set a kitchen timer or use a reminder system to avoid tragic mistakes.

FAQs: Common Mistakes Pond Owners Make During Water Changes

Can I just top off my pond instead of doing water changes?

No, topping off a pond does not remove toxins or concentrated waste—it only adds fresh water. A proper water change removes pollutants while replenishing essential minerals.

How do I avoid shocking my koi with new water?

Always match the temperature as closely as possible and introduce fresh water slowly. Adding it through the filtration system helps mix it more gradually.

What happens if I forget to turn off the hose?

Untreated chlorinated water can burn your koi’s gills, leading to death in just a few hours. Always use Kloubec's Water Preparation and set a timer as a reminder to shut off the hose.

How do I know if my pond water quality is bad?

Test your water regularly for ammonia, nitrites, and pH imbalances. If you notice murky water, excessive algae, or koi acting lethargic, it’s time for a water change!

By keeping up with routine water changes and using the right de-chlorinator, you’ll maintain a healthy, thriving koi pond for years to come.