Cloudy Water in Summer & Clear Water in Winter

Cloudy Water in Summer & Clear Water in Winter: Part 2

Every pond owner dreams of a healthy pond, with happy fish, and vibrant aquatic plants, that stays crystal clear all year round.  Ponds are living ecosystems and require special help during each season.  During the summer, when you want to show off your pond to everyone, the water tends to be cloudy.  Water clarity is a struggle, and algae tries to take over.  When the weather gets cold and you only go outside to check up on your pond, the water is perfectly clear.  Earlier this year, we explored how to combat cloudy water in the summertime.  In part two of the blog, we are going to focus on extending the winter clarity.


Why Water Is Clear in Winter?

You may have noticed your pond is a little less active during the winter.  All of your pond life slowly becomes sluggish, as the temperature drops.  During the summer, your pond is the place to be.  Fish, frogs, and turtles, frolic in the water, cooling off from the heat.  Your fish happily swim up to greet you, hoping for a snack, whenever you pass by.  Now your fish stay at the bottom of the pond, barely moving, and they are not eating very much, if at all.  The lack of movement in the winter naturally keeps the water clear, allowing the sediment to settle.


Winter Maintenance

Clear water in the winter isn’t a work of magic.  Your pond needs a little help to transition through the fall and winter.  Properly closing your pond down in the winter will help to ensure a healthy reopening in the spring.  Even though the water may look clear in the winter, there can be other issues hiding beneath the surface.


Algae and other bacteria are less active during the winter, which is why you rarely see green ponds in December.  Pond owners typically do not have to battle algae once the weather cools, but oxygenation is still a major concern.  If the surface of the pond freezes over, the water can not oxygenate and release gases.  A 6 or 8 inch hole should be kept open in the ice at all times using an aerator or de-icer.



As the weather slowly warms bringing more sunshine, you can start preparing your water for the spring.  Ideally in the fall and winter, before the pond is closed, the focus was on debris and keeping any organic materials out of the water.  The sediment and sludge at the bottom of the pond are less noticeable in the winter, because the pond pump and fish aren’t agitating the water.  In the spring, the fish begin to wake up from their winter nap, demanding food, and start to become more active.  The activity of fish and the reinstalled pump can create cloudy water.  Any debris that settled at the bottom of the pond during the winter will be attractive to algae in the spring. 


How to Extend Water Clarity

Beneficial Bacteria

Bacteria are less active in the winter time, and need a boost once the water temperature rises.  Beneficial bacteria break down excess nutrients in the water without releasing harmful gases and byproducts like the bad bacteria does.  Many beneficial bacterias will not work in very cold water, and are not recommended until water temperatures are consistently above 50°F.  Boosting your beneficial bacteria is a simple way to begin combatting cloudy water before it starts.



Closing down your pond is the perfect time to clean and examine filters.  The filters will have to work extra hard once the pond is reopened to extend water clarity.  There are three types of filters: mechanical, biological, and UV.  Mechanically, filter pads physically remove any small debris in the water.  Biological filters use beneficial bacteria to break down nutrients.  UV clarifiers eliminate algae and microorganism using UV light, as the water passes through the filter.  When you reopen your pond, it is a great time to replace your UV bulb.  Check that your filters are working efficiently and are properly sized for your pond.  The smartpond® calculator is a tool to learn your pond’s size, and it can help you determine if your filters are sufficient for your pond volume.  


Reduce Sunlight

Algae need two things to grow, nutrients and sunlight.  When your pond opens for the spring, there is usually a lot of excess nutrients built up from the winter.  Leaves, lawn clipping, plant parts, and fertilizers, find their way into the pond during the fall and winter, and are not broken down by the bacteria once the water becomes cold.  The algae does not grow because the water is too cold, and there’s not enough sunlight.  Most floating plants cannot survive the winter, and the longer days of spring bring direct sunlight and warmth.  Your pond can quickly have an algae bloom.


Reducing the amount of direct sunlight that reaches the pond can help prevent algae from turning your water green.  Pond tint helps prevent the sunlight from penetrating the water.  It also gives the pond a nice blue hue as an added bonus.  As soon as the water is warm enough, you should replant your floating plants, as they help block the sunlight.  Aquatic plants will also help absorb the excess nutrients in the water.



Oxygen is incredibly important to water clarity.  Beneficial bacteria are aerobic; they require oxygen to survive.  They work more quickly than the bad bacteria, which is anaerobic, and doesn’t need oxygen.  Beneficial bacteria rapidly break down nutrients into harmless compounds.  The bad bacteria work slowly, releasing harmful gases that contribute to algae growth in the process.


In still ponds, only the surface water is oxygenated by the wind or any other natural water disturbances.  The bottom of the pond becomes devoid of oxygen, and the beneficial bacteria die off, leaving the bad bacteria to work.  Aeration from waterfalls and fountains pull water from the deeper parts of the pond and spray them into the air, circulating and oxygenating the water.  An aerator diffuses water directly into the bottom of the pond, and as the bubbles rise, the water is mixed and oxygenated.


Having clear water in the winter and cloudy water in the summer can be frustrating.  Clarity is not always a sign of quality.  Winter is a slow time for ponds, the lack of movement allows the sediment in the water to settle, which leads to clear water.  When spring arrives, the nutrients that built up during the winter become food for algae, when combined with warmer water and sunlight.  The fish are more active, which can stir up the dirt, causing cloudy water.  You can extend the clear winter water with a little extra care before spring.


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