overheated pond

overheated pond

The perils of an overheated pond

August is a good time for things to be very hot—even an overheated pond!  August doesn’t just bring about the end of summer and one more month of summer fun.  It also means one more month of HOT weather—hot enough to cause problems.

When it stays hot outside for a while, your pond water can get too warm.  Once the water temperatures hit 80F and above, things in your pond may change.  You may notice stressed out fish, struggling for air.  Your plants may look a bit droopy as well.  So what exactly is happening and how can you help your pond and fish?

The problems of fish in an overheated pond

Warm water has a low capacity for holding oxygen, while cooler water can hold large amounts of oxygen. As the water becomes warmer, your fish become more active. That increased activity means the fish require more oxygen when less oxygen is available to them.

Fish aren’t the only pond dwellers to increase their activity. Bacteria, viruses, and parasites also tend to increase which means diseases can spread quicker. Just like humans, stressed fish are more susceptible to diseases when they’re not feeling well. Since most pond owners stock their water gardens with cold water fish, it’s even more important to be aware if your pond is becoming uncomfortably warm.

Problems with Plants

What happens to your plants when you have an overheated pond? Your pond plants might start to show the effects of extreme heat. Water lettuce and water hyacinth can turn yellow and burn.  The pads of your waterlily might also begin to turn a brownish color and start to decay.

Since the leaves of a waterlily help shade the pond and keep it cooler, maintaining the plant’s health is a priority. Fortunately, it takes a long time for pond water to reach 80 degrees, and you have some solutions available to assist with cooling.

How to help your overheated pond

Ponds with a depth of two feet or more have an advantage over shallower ponds, as the bottom of the pond will remain cooler and the fish can hang out at the lower depth.

Water plants also help cool a ponds and should cover one-third to one-half of the pond’s surface area.  Waterlilies, mosaic plant, and water lettuce are all great options for shading the surface of your pond. Natural overhead shade from trees, bushes, and even your house will help.

And finally, keep in mind that your waterfall or stream plays a huge role in the oxygenation of pond water. Oxygen enters the water when there is air and water interacting. Streams and waterfalls increase oxygen levels by increasing turbulence.

More help for your overheated pond

You can use a pond thermometer to check the temperature of your pond water. If you find the water nearing 80 degrees, you can increase oxygen with a pond aerator. We can provide this aerator for you.

Keep in mind, you don’t need to take your pond’s temperature every day – especially if you have an ecosystem pond with proper circulation and filtration. Simply watch for tell-tale signs like fish gasping for air at the surface of the water or near a waterfall. That’s typically the first sign that the pond is overheated and needs oxygen.


Have more questions or need to cool down your overheated pond? Reach out to us for more info!