captain039-recponds wrote:

I should have asked if below zero weather will kill the algae we now
have, or if it would be wise to use an algaecide or something else?

Yes, it will - for the most part. It's _never_ wise to use an algaecide in
a fish pond. You aren't doing anything to solve the main problem -
nitrates - and you can only hurt the fish.
--
derek