Pottsy - Today, 31 Oct, our NW Ohio water was 49 deg F and visibility with the "white" disk was 4'. My 'Terribly clear' is 10' to 14' which is where my pond usu is right before and ofter ice out.
Water Visibility Note: imagine getting up in the morning and only being able to see 4 ft to 5 ft out the window and calling that "clear". Now imagine how thick the fog or particles in the air would have to be to only see for that short of a distance! Well that is your water. As an alternate imagine how thick the air particles would have to be to only see 50-80 ft or at the other extreme, fertilized range of 16"-24". Tremendous numbers, no gigundous numbers, of very tiny and even smaller things in it! Has to be there, for visibilities to be so short.
I propose, just before first ice over which is probably in two to three weeks for you, I get you a sample bottle by mail with some algal preservative in it. Collect a shallow subsurface grab of water pour it into the bottle and send it off to me. We will have a look (1000X) at your 'terrribly clear water'. You won't believe the results and it will only cost you the postage. Or alternative - get some Betadine (iodine skin/wound cleanser) from the drug store (cheapest you can find -Walmart Brand) and use your own small 2oz to 5 oz plasic bottle add about 1/2 teaspoon Betadine to 5 oz pond water; mail it off.
PS: It is common to have areas that are a little clearer or cloudier than the others. "We" call this patchiness and the cloudier areas are due to the living organisms (phyto & zooplankton mostly) collecting or clustering together resulting in cloudier conditions. Clearer areas are a lack of organisms which have clustered. This also results in uneven heating of the water and forming "warm spots". You've probably felt them while swimming.
