Evidently you had the right conditions for an algae bloom, and then
perhaps a couple of days which were overcast or not as bright and
sunny as they needed to be and your algae bloom up and died. That
will cause brown water almost overnight. Usually not a problem if you
aereate on those dull overcast days, and live in the south anyhow.

Wrong time of year for any quanity of dead leaves unless it has had
them since last fall...........but that will do it as well.

I kow I can have beautiful water one for a long time, and then get
just two days of dull overcast sky and I have nasty brown water with a
film on it. Needless to say I keep an eye on the weather and aereate
often.
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