3 Things You Should Know About Ponds In Cooler Temperatures

There are two types of people, those who prefer sweater weather and those who wish it was summer all year round. Like people, ponds can flourish in any season but have special needs to succeed in different temperatures. During warm weather, the main concern is algae blooms, water quality, and oxygen levels. There are three things you should know about ponds in cooler temperatures; the decline of good bacteria, fish vulnerability, and potential runoff exposure. 

The decline of good bacteria

There is less direct sunlight during the fall and winter as the days shorten and the pond becomes cooler. The beneficial bacteria (the type you want in your pond) become less active and lie partially dormant once the water temperature falls below 50 degrees. These bacteria are significantly more effective at breaking down organic material than the other types. 

Towards the end of summer, you want to make sure your pond is as clean as possible. You can use a pond vacuum to suck up any debris at the bottom of the pond if there is a lot of buildup. Avoid doing a total water change, as it will eliminate the good bacteria (new pond syndrome). You can use water treatments containing colonies of good bacteria like Sludge Remover to build up the bacteria and break down debris. 

During the fall and winter, debris settles at the bottom of the pond, where the fish will need to stay as the ice builds up on the surface and begins to decay. As it decays, it releases harmful gases like ammonia which decrease oxygen levels. This is why you need to keep an area of the ice open and add an aerator if your pond is deep so the gases can release as the water oxygenates. 

Fish vulnerability

Fish are cold-blooded creatures, and their metabolisms and bodies slow as the pond water cools. When water temperatures are below 50°F, they move less and no longer require food until the water warms back up again. This increases their vulnerability to predators. 

Some plants lose leaves, die off, and must be trimmed back to prepare for winter, exposing the now-slowed fish even more. Daytime predators like water herons have a harder time catching the fish once the ice forms. The fish can more easily avoid the opening in the ice. Predators like mink and raccoons are nocturnal and are not deterred by ice. They sneak in through the opening and prey on the lethargic fish. 

Fish need hiding spots at the bottom of the pond to escape the predators. Small plastic crates, empty pots, and PVC pipes can add a much-needed area of safe haven and protection for koi and goldfish. Adding a Pond Tint or pond netting can also give fish an extra layer of security in the colder months. Pond netting is great for keeping pesky fall leaves out of the water but can be used throughout winter to help keep your fish safe from predators! 

Aeration is always recommended year-round to help keep oxygen levels high, and it can also create an opening in the ice-covered surface of the pond during winter. This gives the extra bonus of creating water disturbances near the ice opening to deter predators.   

Potential runoff danger

Common lawn and plant fertilizers contain nitrogen compounds and phosphorus, which help algae bloom. Fertilizers used in the summer will begin to make their way to the pond as the weather warms and the ice melts. This creates perfect conditions for a spring algae bloom.

Try to avoid using fertilizers or pesticides in the fall as a precaution. Liquid melting agents and salts used to make pathways in the winter ice can disrupt the pH levels. If your pond is built on a decline or in an area you worry will be subject to runoff, you can build a slight ridge around it and line it with rocks and other plants. Runoff can also be an issue during rainy seasons as well, so the ridge will add protection year-round. 

Pro Tip: In the winter, if your pond is deep enough so it won't freeze all of the way through, you can light up your pond at night with pond lights. Just place them in the deepest part of your pond to avoid any damage from freezing. 

Ponds need a little TLC to make it through the winter, especially when filled with fish. The weather cools, and life slows down for everyone. Ponds are subject to the decline of good bacteria, fish vulnerability, and runoff during cooler temperatures. There are small things you can do before winter peaks to ensure your pond and its inhabitants are ready.