Mid-April is spring start-up season for pond owners in Minnesota. A common question we hear during this time is, “Is it too cold to start my pond in Minneapolis?” (I mean, the ice just melted a few days ago….!) Here is an answer from Jeff, who helps start over 100 ponds each spring.
Jeff: “The short answer is, “No. It is not too cold to start your pond. Add starter beneficial bacteria.”
“If the temperatures are above 10 degrees, it is warm enough to run your pond. Add some starter bacteria, then add cold water bacteria (if the water is below 50F) or regular beneficial bacteria if the pond water is above 50F. A digital thermometer helps, too. “
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In cooler weather regions, where temperatures stay above 10F ( winter temps:10F for lows-40F for highs), moving water will form amazing ice sculptures over the falls and edges of ponds but in Minnesota, pond owners have to completely shut down our waterscapes because of ice forming on the bio-falls and waterfalls. A small amount of ice is beautiful and fine for a pond. A large amount of ice alters the water flow.
What pond owners in northern climates such as Minneapolis/St. Paul, Canada, or Wisconsin struggle with is the deep, sustained cold when the water freezes into ice dams which can cause a pond to “run dry” because the water has frozen on top of itself as it pumps. Then, in spring, pond owners in Minnesota have to wait for the frozen ground to thaw before we can complete the startup process.
Water in the sun thaws faster than soil. We regularly find ice in underground pipes even if the pond water is open. Pondless waterfall basins are notorious for taking forever to thaw in spring.
A second question that routinely pops up with Minnesotan Spring weather is, “There is algae in my pond! What do I do?”
The first two plants to greet us in spring are algae and marsh marigolds. Both plants love cool weather and are able to grab nutrition from water to grow like crazy! Algae growing in your pond means there is plenty of nutrition.
A few algae control options are poisoning the algae via copper-based algicides or removing nutrition with other plants or bacteria. Because heavily feeding aquatic plants generally are not growing much in the very early spring, especially lush tropical plants like taro or cypress, we strongly recommend a solid dose of starter bacteria followed by daily cold water bacteria treatments for a week.
As the water temps start hitting 50 degrees and the air temps are a minimum of 45F at night, its time to switch to regular pond bacteria. If you don’t have a fancy thermometer that can link to an app on your phone, stick your hand in the water. When it no longer hurts to stick your hand in and hold it in for 15 seconds, it is probably time to switch to regular bacteria. Remember, air temperature is not water temperature!
Happy Spring in Minnesota, where we do love spring!
For further reading, check out this post on “Three quick ways to control pond algae”.
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