news from the waterfront by Tim Matson
Old ponds are like antique cars. Potentially very valuable, often in need of work. Why so valuable? Well, like the old DeSotos and Model Ts, they don’t make ‘em anymore, hence the rarity factor. How does this apply to ponds? Some of the best classic country ponds, the great fishing and swimming holes, were built in ideal locations for pond building: wetlands. Easy digging, and plenty of water. However, to protect our diminishing wetlands, we’ve put many of those classic undeveloped pond sites off limits, or protected by a barrier of time consuming and expensive permitting, with no guaranteed green light at the end of the process. Imagine what that does to the value of a forty year old pond dug before pond prohibition. Ye olde pond, now grandfathered in legally and perhaps even considered a protected wetland itself… well, they just don’t dig ‘em like that anymore.
Now imagine yourself with just such a classic pond, proven water supply, and just one little problem. Senioritis. It may have silted in with sediment runoff and organic matter, leading to water quality problems. Problems like algae and low dissolved oxygen, too much phosphorous, off-balance pH. Not much good for swimming or fishing, and probably getting worse every year.
Unless you want to see your pond take the predictable path to oblivion (filling in naturally until it becomes again the wetland it once was; eutrophication it’s called), you’ll want to do like the antique auto restorer, and get to work.
Restoring an antique pond will generally involve one or more of a few key operations:
First, a water test to evaluate the chemical basics: pH, dissoved oxygen, perhaps phosphorus and nitrates. That will help you determine what you may need to add to the water (lime, oxygen, etc.) and/or take away (sediment, inflows of contaminated or poor quality water (perhaps well water with low oxygen levels that need a boost).
Now it’s time to consider various restoration approaches.
*Physical cleanout to restore depth and remove organic matter that might be using up valuable oxygen. (Usually not inexpensive.)
*Mechanical aeration of the water to add oxygen, which will help decompose the nutrients that feed algae problems, make up for the oxygen debt, and mix up pond water to get some of that cool water up top where it may benefit fish in summer. (Less expensive than dredging, but will still lighten your wallet.) Aeration may require a careful, slow start, to prevent changing oxygen levels from harming fish.
*Use of non-toxic chemicals, beneficial bacteria, or helpful plant matter to boost dissolved oxygen levels and decompose unwanted sediment and organic matter. (Most frugal of all.)
Aeration is the quickest way to boost oxygen levels and destratify water. Some aerators pump air down to the bottom of the pond, where it rises in a plume of bubbles to boost oxygen levels and help circulate the water. There are also surface splash type aerators, sometimes combined with a fountain, for both water improvement and aesthetic effects. Paddlewheel aerators are sometimes used in emergencies by fish farmers to stop a fishkill with fast infusions of oxygen. However, for general pond use, submerged aeration is generally considered the most effective and economical. There are pros and cons to various systems, costs, optional installation setups, and running schedules; check with a reputable aeration dealer to discuss your needs. Fresh-Flo has years of experience with aeration and pond water quality improvement; give them a call, or check their website for further details.
It’s also possible to use non-toxic chemicals, beneficial bacteria, and plant matter to improve water quality. In pond recirculating systems ultra-violet water treatment is sometimes used to knock off baterial problems, but I’ve heard this may also result in loss of beneficial bacteria. Incoming water is sometimes filtered, for example through a sand medium.
Chemicals, beneficial bacteria, and plant matter like barley may be especially helpful at ponds where you may not have electricity to power an aeration system, or you don’t want to run an aeration system 24/7, which is the recommended rate during warm weather. In fact, some grasses and grains were among the earliest pond treatments, and are still used today. Barley straw is used in submerged bundles, and also compressed form, as a water treatment. As barley decomposes, it produces hydrogen peroxide and kills algae. Still Pond Farm is a good supplier of barley straw and other water amendments.
Some quicker acting chemicals can also be used to boost oxygen levels to help decompose organic nutrients. And compounds of beneficial bacteria can also be used to help control unwanted algae as well as decompose accumulated sediment. Chemicals and bacteria may be formulated for use together, for most efficient water treatment. Applications of chemicals, bacteria, or plant matter will be most effective at correct water temperatures. Good water circulation will help move the additives around. It may be helful to jump start some bacterial additives by adding water to a dry product before dosing the pond, kind of like getting your yeast kick-started before bread or beer making.
Pond before treatment of algae
Clearpond.com is a pioneer in formulating non-toxic amendments for pond water improvement. They’ve been in the pond water quality improvement business for three decades, and if you’re looking for experienced advice on products to improve your pond water, give them a call or visit their website. Keep in mind that in some states, adding chemicals, non native plants, or fish for plant control may be regulated; check your supplier and natural resources department if you’re not sure.
Pond after treatment of algae
Photos courtesy of Clearpond.com.