Understanding Pond Stratification & Aeration

Thermal stratification in a pond means that there is a noticeable temperature difference as the water gets deeper.  Normal thermal stratification begins to occur in May and can continue through September.  The cold water at the bottom the pond supports anaerobic bacteria.  This bacteria is not helpful in decomposition.  When leaves and other organic matter are deposited on the pond’s floor, they will not decompose quickly and black pond muck will form.  Installing an aeration system in the pond will lead to more aerobic bacteria throughout the pond.  This is the bacteria that will aid in decomposition.  If the black pond muck is allowed to accumulate, the pond may need to be dredged which can be costly. 

Muddy Pond Water

Many ponds are built to provide recreational activities and aesthetic benefits.  Chronically muddy water makes a pond unattractive and most swimmers will avoid swimming in such water.  Fishing is impacted because a chronically muddy pond reduces the amount of sunlight penetrating into the water which in turn reduces the amount of aquatic food produced by the pond’s food chain.  This will reduce the amount of fish biomass that can be supported.  High turbidity levels negatively impact the ability of bluegill and bass to feed and maintain themselves in a healthy condition.

The two primary biological causes of muddy water are fish and waterfowl.  Large populations of the common carp, goldfish, and bullheads can cause muddy water due to their spawning and feeding activities in shallow water.  Large numbers of ducks and geese cause similar problems.  Also, waterfowl often eat bank vegetation which can increase erosion. 

Watershed activities can also lead to muddy water.  Ponds that receive runoff water from nearby soils that are frequently disturbed with agricultural equipment are prone to be muddy.  Construction within the pond’s watershed can also result in considerable input of suspended clay into a pond. 

Muddy waters can be controlled by removing invasive fish species and keeping waterfowl away.  Products such as flocculants can also be added to the water that will cause the suspended particles to bind and sink to the bottom.    

Lynch, William E. Muddy Water in Ponds: Causes, Prevention, and Remedies. The Ohio State University Extension. 

Feed your Goldfish and Koi the appropriate food for the season:

Now is a good time of the year to switch your fish food to a Spring and Autumn staple food.  When the water is cooler fish will digest their food much slower.  Because of this, your fish need to eat food that will fully digest and not be left in their stomach too long.  Pondcare Spring & Autumn Premium Pellets contain the proper portions of protein, carbohydrates, vitamins, minerals, and amino acids for coldwater feeding. 

Cattails:

Early fall is the best time of year to treat cattails that may have invaded your pond.  Cattails can grow anywhere from 3 to 10 feet tall.  In the Unites States, cattails are either the broad-leaf or narrow-leaf varieties.  They reproduce by wind-dispersed seeds or through their root systems.  Most cattails only require 1-2ft of water to grow to their full potential.  Once the plants have established, it will be very difficult to maintain open water. 

Cattails can be controlled using Glyphosate, a systemic herbicide.  This product is best applied in the early to mid fall when the cattails are starting to take all of the nutrients out of their leaves to go dormant for the winter.  When the Glyphosate herbicide is applied at this time, it will be taken down into the plant’s root system along with these nutrients.  This will ensure that there is very little re-growth during the next season.    

Watershed Maintenance:

The watershed is the area of a land where the water will drain into a nearby body of water.  If the area of land outside of your pond contains nutrients from fertilizers, manure, or goose droppings, these nutrients will be washed into the pond.  The excess nutrients in the pond may cause algal blooms.  If the source of the nutrients cannot be eliminated, the next best management plan is to plant nutrient absorbing plants in the watershed area and around the pond.  Rushes, irises, and tall grasses have large root systems that can absorb the nutrients before they drain into the pond.