Question
Well good morning Tom, oh, and Happy Thanks-giving.
Our location is Ontario, right near Lake Erie.I think they classify us as zone 4 (for plants). Our weather can go from a summer consisting of 90degrees to a winter of -17 (sometimes even colder - yuck) I hope this will help.
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Followup To

Question -
Tom,we put a pond this past Spring and we've never had a problem at all. Which was hard to believe by most people considering it's our very first one and definately not the last. But now that the weather is getting colder we seem to be over grown with green algea. Nothing we do seems to be helping. The water temp is 59 degrees.  So any info would be great.

Answer -
Hi Deanne,
Before I answer your question, what is your location?
thx,
Tom

Answer
Hi Deanne,
Thanx for the extra information.  Have you tried using barley bales?  They are available at the nursery or on the Internet and they do work.  I have used them.  All they are are small squares of barley straw.  They have a natural chemical in them that inhibits the growth of algae but does not harm fish or other plants.  Try that.  I'm sure it will work.  By the way, I love visiting Canada.  I have been to Toronto, Montreal, Quebec City, Ottawa, New Brunswick, Prince Edward Island, Nova Scotia and Victoria.  You have a very beautiful and friendly nation.  I hope to be going to Vancouver and Calgary next year.  I hope my information helps.
Take care.
Tom