The water in my pond had been murky with about 12" to 18" of visibility since late August. I ascribed this to die off of watershield and other vegatation.

We finally have some fall like weather with a couple days of temps in 70s - noticed today that water was clearing up and more like 18" to 24" visibiity. Does lower water temps make the water clear up?

Cool water lowers any fish activity, like spawning, that might stir up the bottom debris / muds. Plankton also grows less. My clearest water is usually from mid to late December to late January. A clay pond with suspended clay that doesn't settle out in a "jar test" won't clear much in winter.

I'm seeing the same thing in my pond in Michigan, ncvdl:

I'm pretty sure mine was not from a lack of fish (or crayfish) action on the bottom but rather my summer time 'bloom' is fading away. The last few years the bloom revs up as water temps get up there, and it lingers into August. Then we get some cool nights, water temps dip and bloom stops. We get gradual clearing for a week or two and tonight I noticed too that in the shallows I have really clear water. I can watch the larger minnows come tearing in from the deep and grab the pellets, whereas before I never could see the fish only see the splash.

The murk in your case may be a bloom.

Temps do not seem to have much effect on how clear or not so clear the water is in my pond. And temps are on the way down, calling for possible frost/freeze over the next few nights. But this is Michigan and it can happen anytime now.

I just noticed my local strip pit I fish in has the clearest water of the year right now. here in central MO

Same here.. Pretty normal for the fall time period. Planktonic activity drop, metabolism slowing in all summer creatures, less activity over-all, yep.

My pond cleared up from 30" of a nice green color to where it is now @ 45". It was most likely caused by colder water temps due to my aeration being down for a week without my knowledge and the pond developed a thermocline. When I discovered the lack of aeration, I did the repair and started up the system. This caused the colder water to be dispersed throughout the pond and that is when my plankton got diluted back. My biggest concern is the possibility of my TFS not having enough food to fatten up for the winter which might effect their survival in the cooler water temps this coming winter. I am thinking if I fertilize the pond to get the bloom back I will be feeding my bushy pondweed and my American pondweed and I will not get my bloom back. So, my pond cleared due to cooler water but was not caused by our unusual hotter fall temps or the lack of cooler weather we have been seeing this year.

I went home last night a put a bag of ice in the pond. Same results lol. Anyone have an ice truck.

This has all got me thinking how upset I am with my water clarity. I have a lot of grass growing around my 2 acre pond but visibility is still only 4-6 inch on sechi disc. I honestly thought it was a bad algae bloom. Water color is coffee with way too much cream in it. decided to do a jar test this evening. Filled a quart jar and a pint jar. In the pint jar I added 1/4 teaspoon alum to it and shook it up. In only 2 hours it went to perfectly clear you could read a newspaper thru it!! Everything settled to the bottom. So I guess it was clay particles after all.I had checked water chemistry before I added anything and everything was pretty good except hardness is still only about 10. Ph was about 7.2.I do run my aeriation 24 hours a day. I tested the water in the jar with the alum and readings went very bad!! Went from 40 alkalinity to 0!! And the ph would not even register on the scale anymore so was way below 6. Ok, what and how much do I need to do to my pond to get it clearer where I can enjoy looking at it??

I think some of the answers may be in this thread (see link below) if you start reading from the beginning. I'm impressed at several threads that document how well the right amount of Alum plus the pH buffering affect of calcium can clear a pond and keep it clear.

The exact answer for your situation can come from Rainman if you give him an idea of how big your pond is, average depth, how much water and then what your chemistry is in the pond.

Give some thought also to what is stirring up the clay and keeping it suspended in the water (water flow, rain run off, catfish, crayfish, or just who knows why?)

Alum vs CLAY!!

My first pond was very clear and had lots of FA a couple of years ago. I got five Koi the spring of 2018, grew them out in my sediment pond, put them in the 1/4 acre pond last fall. No FA this year as something (I suspect the Koi) has limited visibility to about one foot. The Koi are about 15 inches or more now.
I also stopped pumping creek water in after last year. That might also have some effect on clarity, IDK.

I have decided I would rather have muddy water than loads of FA.

Flame, you and I both run the Kasco aeration system and in my case the diffusers would kick up bottom sediment and keep the water a little off color. Had water tested by Mr. Bill Cody. Bill came back and said it was most likely detritus. Crap on the bottom of the pond being mixed up. After trying many different things, cinder blocks etc. to eliminate that possible problem I finally built some tables from rebar. Tables are 21" high and the bubbling tubes are about 10" or so above the diffuser base, so my bubblier tubes are now about 3' off bottom. That helped a lot.

I also added alum/hydrated lime because of the water had an ugly green color. I mean it was not a good color. I think it came from me adding a product to reduce the nutrient level. So, I added around 80 bags of alum and 40 bags of hydrated lime. This was a few less than what I came up with when testing how much to add. It worked great. Water cleared in a couple of days and a week or so later it settled in at or around 32" of visibility. My pond is 3 acres and I think your is two. I am guessing or water depths are fairly close to each other. This might give you an idea on how much to add, even though no two ponds are the same. A downside for all of this is when the water clears, plants will start up in the pond waters. Something else to manage lol. I am picking up some grass carp this coming Sat. Hope this helps.

Rainman, I tried to send you a PM but it says you are over your private message limit?? Can you read my post above about my jar test and send me a PM if you can? My pond is approx. 2 surface acres dug almost exactly 5 years ago. Only have lmb cnbg and res.Deepest part is 11 1/2 foot. Average depth about 4-7 foot. 3 aeriation diffusers running 24 hours a day in the 11 foot water.Jar test with alum did kick but to perfectly clear in really only about one hour. I need assistance please!! I have almost zero FA and fish are thriving very well with lmb probably up to 8 pounds.

Yes - I think the dying watershield was fueling a bloom.