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Tips for Keeping the Water Clear in Your Koi Pond

How to Keep Water Clear in Koi Ponds San Diego, CA

Clear, clean water is essential to maintaining a healthy environment for the fish in a koi pond. Additionally, after you’ve put time and energy into building your pond, the last thing you want is algae and murky water ruining your view. Luckily, there are some easy ways to ensure the water in your koi pond stays crystal clear.

Don’t Overpopulate

A good rule of thumb is that your pond should have no more than 10 inches of fish for every 100 gallons of water. To be clear, this generalization is taking for granted that you have very good filtration. Because fish waste is a major contributor to algae growth, having too many fish in a small pond is one of the main causes of excessive algae growth. Aside from being unsightly, too much algae can diminish water oxygen levels, which can be fatal for fish. If you find you have too many fish for the size of your pond, consider finding a new home for a few of them.

Choose the Correct Pump

A pump is one of the most crucial koi pond supplies, and the size of your pond is one of the most important factors when choosing a pump to buy. If the pump is too small, it won’t circulate the water properly. Stagnant water causes low oxygen levels and poor water quality, which in turn leads to sludge buildup, murky water, and unhealthy fish. Once your pump is installed, check it frequently to make sure it isn’t blocked by debris and that it’s working properly. Of course, the pump for filtration must be left on 24 hours a day. Without the oxygen-sustaining water being fed to the filter, the beneficial bacteria would die off quickly.

Keep the Pond Clear of Debris

Leaves, mulch, branches, and other debris can fall or wash into your pond and decay, which causes sludge buildup that can be unhealthy for your fish. A small amount of sludge is inevitable, but it’s best to prevent major sludge buildup from the start. Avoid placing a pond directly under trees if possible, and if you notice leaves or branches in your pond, clean them out before they start to decay. If you find yourself with a sludge problem, adding beneficial bacteria can help you get your pond water clear again. Beneficial bacteria is a supplement that can be purchased in dry or liquid form. We recommend Microbe-Lift:


Beneficial bacteria is something that should be added every 6 months to re-stimulate the breakup of waste buildup that accumulates.

Don’t Overfeed Your Fish

Feeding your fish too much or too often can have several negative results, one being that it can impact your water quality. The increased waste fish produce from overfeeding can cause algae blooms, and uneaten food in the water can decay and turn to sludge. Fish should be fed no more than they’re able to eat in 2-3 minutes, and any excess, uneaten food should be removed.

Add Aquatic Plants

To keep algae growth down, add oxygenating plants on the surface of your pond. Some popular choices of aquatic plants include water lilies, water lotus, water lettuce, and horsetail. Aquatic plants consume the nutrients algae needs to thrive. Additionally, floating plants provide shade, which reduces algae growth, and submerged plants increase oxygen levels in water.

Do a Water Change on Your Pond

 We’re not talking about adding water here, which does nothing but refill what evaporated. Instead, take out 10-15 percent of the volume and water your plants with it. This is some of the best fertilizer money can buy. Can you say giant tomatoes?

If you need high-quality pond equipment to properly care for your koi pond and keep the water clear, stop by Aquatic Warehouse in Kearny Mesa. You can also check out the products featured 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
  • Phone: (858) 467-9297
  • Email: sales@aquaticwarehouse.com
  • Working Days/Hours: Mon - Fri / 10:00 AM - 7:00 PM
    Saturday / 10:00 AM - 6:00 PM
    Sunday / 11:00 AM - 6:00 PM


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