Cold Water String Algae Q&A

String Algae

At Nualgi Ponds, we pride ourselves on helping any and all ponds thrive. We recently had a customer write in who was struggling with String Algae in his pond even in cooler weather. He provided us with a detailed account of his situation and our pond expert promptly replied.

Customer Query: String Algae blooming in very cold temperatures in Janurary

I removed the pump in late December when an extremely cold patch of weather (sub zero temps and 12 inches of snow) was to due. However for the first time I put in a pond heater and 2 bubblers to keep the fish comfortable and stop the pond getting covered in ice, which worked well.

I’ve been using Nualgi Natural Pond Cleaner for several years during Spring, Summer and Fall and in 2023 I also started using Nualgi Beneficial Bacteria, Muck Remover and Organic Digester.

2023 was the first year that String Algae was a persistent problem for most of the year, and in addition to using the above listed products additionally I would regularly remove clumps of algae regularly.

When inspecting the pond today (1/31/24) for the first time this year I noticed that, the fish seem healthy. despite the cold temps, but I also noticed a considerable amount of Algae in the pond! 

Is it safe to use Nualgi Natural Pond Cleaner or other Nualgi products with below freezing temps and snow due and potentially due for another couple of months ?
Is it the pond heater contributing to the problem of Algae growth at this time of year ?

Any advice is most welcome.

Thanks in advance

Andy W

Response from our Pond Expert:

Hi there,

String algae pops up out of seemingly, nowhere at times because spores travel around the jetstream winds and drop. But the case of you making a major change could have disrupted a suppression your pond had. Difficult to say which.

Test your water for Nitrate and Phosphate loads. If Nitrate is +10 get it to 10 or below with water changes in spring of 25% weekly. If phosphate is above 0.0, use Microbelift phosphate remover.

pH should be between 6.5 and 8.0. Any higher and string algae could be fueled by that value.

Products are best used in +47F waters. Though you can dose Nualgi Natural Pond Cleaner in quarter doses every two weeks below such temps.

Just remove what you can for now and in spring we shall see where the Nitrogen Cycle sits and tackle it safely.

We’ll continue to work with Andy as we do with all customers on any issues they have into the Spring and Summer. If you have any pond questions, don’t hesitate to reach out to our pond experts for advice. Click below to talk to a pond expert.

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