Pond Talk

Tammy from Iowa wrote to us recently and asked, “We have a small pond, maybe 800-900 gallons. Is it possible to have to strong of a bubbler going? We have about 15 fish and its about 40 inches deep in one spot. We live in Iowa and it will be soon be freezing. Just wondering if too much bubbling can hurt the fish?”

Answer: Tammy thanks for the question! I like to use a small aerator in garden ponds during the winter months, but I would suggest either providing a way to float the air stone or diffuser off the bottom and near the surface of the water, or moving it over to an end of the pond, or even a shelf if you have one. I mention this because you have 4 feet of water depth which is very good. It’s deep enough to allow the fish to go to the bottom and settle there when the weather get’s really cold. The water may be a bit warmer there, and ideally you don’t want to disturb that water, but only keep a bit of the surface agitated.

Unlike the important use of aeration during hot weather, which is a time when oxygen can get low in pond water, in the winter you don’t generally run into that problem so the main benefit of an aerator is to keep a spot of ice open when things freeze up.

Since we’re on the topic of small ponds and winter freeze ups, let me note here that most experts suggest having at least two feet of depth in a pond in order to overwinter fish safely. If there’s any doubt about your ability to winter fish in safety, then it’s probably better to just create an indoor holding tank that’s warmer, well aerated, and filtered adequately.

Pond Heaters And DeIcers

The other option, which can be used together with an aerator, or totally on it’s own is a small pond heater. Most of these are designed to float or be kept at the surface and they’ll do a pretty good job of keeping the ice open even in really cold weather. A few models have detachable floats that keep them near the surface, but they also can be placed at the bottom of the pond to keep more of the water warmer. In most cases, the most important part of this work is really to keep the surface open so that any gases, and things that build up in the water can be released and not trapped under the ice.

Ideally I think in the coldest of conditions, a pond heater is a better choice than an aerator.  These are generally pretty affordable and all you need to do is plug them in.  It needs to be kept in mind that they won’t simply turn on once they power up.  Many of these heaters come with a thermostat built into them so that they only come up, and use power, when the water may start to freeze up.  Above that temperature they’ll remain turned off.

In Iowa we can get a few periods of some really cold weather, such as in January and early February.  If you know some really cold stuff is coming along, then I would have the heater in place and use it as needed.  If you want to run an aerator near the surface when the temps aren’t so brutal there’s nothing wrong with that at all.

Once the weather begins to warm up again, you can eventually move the air stone from the surface, or a shallow area, and back into the deeper part of the pond when the summer comes along.  In other words, we want to aerate the entire pond during the summer, and only a small part of it during the winter.  So bubbles won’t bother the fish at all if you set things up right based on the seasonal needs.

Tom from Wisconsin, a traditionally cold state in the winter time, wrote in and asked if it’s a good idea to use a pond aerator even in the cold months of winter? In addition, his pond is very shallow (around 4 feet deep and about 1/3 of an acre in size) so the particular aerator that would be used might be a bit different than a typical farm pond.

Answer: Tom, thank you for your timely question and it’s one that many people wonder about. The base answer is yes, it’s a good idea to aerate a pond all year round.

Many people know the value of aeration during the hotter summer months, and sometimes they end up learning the hard way that oxygen can get depleted in very warm weather and they lose a large number of big fish as a result. However it’s also a good idea to use aeration if you live in cold weather climates.

Winter Pond Aeration

Cold water aeration isn’t quite as much for maintaining oxygen but to keep an area that’s open from ice. If the pond surface is covered for an extended period of time, and particularly if the pond bottom has some organic build up, or a heavy fish load, some toxic gases can build up and get trapped in the pond, to the potential detriment of any fish.

If an ice hole is maintained, then these gases can be released into the environment and fresh oxygen can be brought in so this is an ideal transfer that keeps a pond and it’s inhabitants a good bit healthier.

Aerators are a good choice for this work because they are generally pretty cheap to operate and if you get a good quality system it should provide years of dependable service. Pond aerators tend to be very discreet in how they operate. They don’t shoot a column of water into the air, but release very fine bubbles into the water, at the bottom of the pond, and these rise up in a column and agitate the surface area just a bit to keep ice from forming.

Shallow Pond Aerators

So with the basics of winter aeration out of the way, let’s discuss more specifically the best type of system for your particular pond Tom.

Over the years a typical pond aerator would have a single compressor that sits on the shore and an airline that runs to a diffuser that sits on the bottom of the pond. Usually if a pond has something like 10 feet of depth or so, you can expect this single diffuser to work well in a pond up to about 1 acre in size. The compressors are usually around 1/4 horsepower. Then as ponds get bigger, you’ll see the compressor get a bit more powerful and additional diffusers will be used to cover the increased area.

This changes though in a shallower pond. Ponds of say 6 to 8 feet or less don’t benefit as much from a single diffuser package. The area this single release point of air would help is diminished somewhat. In other words, the deeper the pond, the more area a single release point will help with.

So the answer to this is to use some smaller diffusers, and usually a bit smaller compressor (stronger compression isn’t as necessary in shallow water) and spread the release points of air out a bit more. Something like a 1/2 acre size pond that’s 6 feet deep might have four small diffusers working in it, rather than one large one. And the coverage and total aeration will be much better with the specially designed system.

Using Shallow Pond Aeration Kits In The Winter

The final part of this answer is fairly important because we want to make sure we keep that spot of ice open in the water. This is less likely to be achieved if we keep the diffusers spread out a great deal, such as we would in the warmer months. So my suggestion is to move these diffusers into a tighter pattern in order to concentrate the agitation caused by the released air at the surface. This is particularly important when you run into really cold weather such as you’ll often seen in northern states like Wisconsin.

In the end, the tighter you make the pattern of released air, the colder the conditions it should be able to help with. In climates that have more moderate conditions, the diffusers could either be spaced a bit wider just as a precaution to any icing that might occur.

Simply put, pond aeration is one of the most powerful tools that a pond owner can use to keep a pond in a better looking and healthier condition. And although you don’t have to do so, using it year round can be very helpful to maintaining fish health and vitality, no matter what season you’re in.

Here’s a helpful video from our sister site at Pond Algae Solutions that discusses shallow pond aeration in more detail.