Pond Boss Forums AERATION Should I aerate? Does aeration hamper clay settling rate

I recently added aeration to my 1/4 acre pond. With a hard rain I get some fresh clay particles suspended, I presume
from run-off. Does the aeration hamper clay settling and should I turn off the aeration for a few days to allow it to settle?

No.

My second pond 1/2 acre got turbid with suspended clay after hard rains, then cleared up after 2-3 days. When I added aeration, it stayed turbid much longer.

In the case of my pond, a front end loader full of limestone screenings (a "floor scrapings" mix that is largely fines, but goes up to pieces an inch or so across, which we keep on hand for several uses), repeated every couple of years, cleared it up for good.

That being said, I wouldn't cut the aeration, but rather figure out how to get the clay settled.

As an alternative opinion, DEPENDING on the amount of water moved per hour, the total pond volume, how long there is active aeration per day in the pond, and the sizes of the silt / detritus particulates, I think bottom diffused aeration can contribute to some slower settling of the finest of the fine or tiniest clay – dirt particulates.

This is my rationale. A fan blowing air in the house I think does help keep some dust particles moving in the air depending on the amount of air moved and the 'wind' air speed. Usually in the house one cannot see dust particles in the air until sunlight shines in a window and highlights or shows dust in the air. Pond turbidity is a "water fog" composed of all sizes and all types of suspended solid particulates that includes bacteria, phytoplankton, zooplankton and detritus / silt / clay particles.

As an example, I just finished analyzing a phytoplankton sample from a municipal reservoir. The secchi disk measurement was 5ft (ntu 9.1). Phytoplankton density was 22,374 cells per milliliter (662,270/oz). The suspended detritus particulates sizes were mostly 0.2-35um wide and were 522,240 particles/ml as 15,458,300/ounce of water! Thus the suspended dirt / detritus was 23 times more abundant compared to the phytoplankton density.
Note that usually stain in water is generally caused not by suspended solids but dissolved substances such as humic acid and dissolved minerals.


I often tell people when they have turbidity issues, to measure the water clarity preferably with a Secchi disk, then turn off the aerator and then every few days remeasure the water clarity to see if the water is getting any clearer with the aerator off. If the water is clearer with the aerator off, then maybe,, and only maybe the water mixing and currents were helping to keep the majority of the microscopic particles suspended in the water column. Note that numerous other physical factors can also play a role in causing suspended particulates to settle well in the water column. Just one of those factors can be various types of plant photosynthesis activities. Another one can be biological activities.

Reference: The smallest clay particles in water, often called colloidal clay, can measure less than 1 micron (or (0.001mm), with some fundamental "ultimate" particles reaching smaller sizes to the sub-micron sizes. Overall, clay particles as a general SOIL category are officially classified as anything less than 0.002 mm (2 microns) in diameter. Normally all the phytoplankton samples that I analyze, the tiny detritus and ‘dirt’ particles (0.1 to 50um) are always 10 to 100+ times more abundant compared to the total density of the phytoplankton.

In comparison dust particles in air typically range from 1 to 100 micrometers (μm) in size. To put that into perspective, a single human hair is about 70 μm thick. Dust Particles larger than 50 μm usually settle quickly, while those smaller than 30 μm easily stay suspended in the air. I assume that tiniest clay particles in water will behave similar to dust in air and both could remain in suspension due to measurable air or water movements.
Because tiniest clay / detritus particles are extremely fine, their large surface-area-to-volume ratio causes them to stay suspended in the water column as colloids. Their dimensions are smaller than the wavelength of visible light (0.0004 mm 0.4um) to (0.0007 mm 0.7um), meaning they cannot be seen with ordinary microscopes and require an electron microscope for observation (from AI).