Keeping unfrozen drinking water available for the flock is something everybody spends time thinking about if they keep chickens in a cold climate. And because so many people are thinking about it and seeking information on it, pretty much everybody and anybody who has ever written about chickens eventually gets around to penning an article on it. I finally tackled the subject a few weeks ago.

When I was researching my article, I was surprised that a whole lot of folks who write about chickens seemed to think that floating a few ping-pong balls on the surface of a water container would slow down or prevent ice formation. While there is definite scientific validity behind the idea that moving water develops surface ice more slowly than standing water, I really doubt that a few ping-pong balls floating on the surface would create enough water movement to make any real difference. And that’s what I said in my article: “Scientifically valid, but the way it’s applied here, not so much.” I summed up my opinion on the ping-pong ball concept by suggesting rather than having unfrozen water, anybody trying this solution would have “frozen water and very cold ping-pong balls”.

Very few of the articles that I read touting the ping-pong ball solution claimed that the writer had actually tested the concept in their own coop. As a matter of fact, the similarity of language in many of the articles suggested that many writers simply borrowed the idea from other writers with the assumption that if it was written down it had to be true.

But what proof did I have that the ping-pong ball idea didn’t work? Every article I could find on the subject of ping-pong balls and water came down on the side of them preventing or slowing water from freezing. But I couldn’t find any evidence that anybody had actually run a controlled experiment. So, I ran one.

The Great Ping-Pong Ball / Frozen Water Experiment

Literature Review

By doing a Google search, I quickly gleaned 15 articles that discussed using ping-pong balls to prevent water from freezing. Of the 15 articles, only three mentioned that the writer had actually tried the ping-pong ball idea prior to writing about it:

Article A—"What we found was the ping pong balls were hit or miss on whether or not they would prevent the water from freezing…But…it’s worth giving a shot.”

Article F—"To help the water from freezing right away, I place 4 or 5 ping pong balls in the black rubber bowls that I use for water in the winter.”

Article I—"I’ve had marginal success with this, but other people swear by it..”

None of these three articles provide what I would call a glowing endorsement of this method.

Why do the authors of these articles think ping-pong balls delay the water from freezing? One writer suggested it is because the balls “break the tension on the surface.” All of the other writers were in agreement that that it had to do with the movement of the balls, saying the balls, “float around,” “agitate the surface,” “bob and float,” or “move in the water.” A few of the writers had no suggestion for why the balls moved around, but two said it was because chickens would peck at the balls and eight claimed that the wind/breeze would blow the balls around.

The Science of Freezing Water

The fact that moving water freezes more slowly than standing water has been scientifically validated and can be observed in nature: Streams flow freely with no ice on their surfaces while nearby lakes are completely covered with a sheet of ice.

Any container of water, be it a lake or a pan of water in a chicken coop, will be coldest where it is in contact with frigid air—at the surface (and also along the sides of uninsulated water containers). As the water at the surface cools, it becomes denser and sinks to the bottom. This process continues until the water temperature reaches 39.2 °F (4 °C). Below this critical temperature, something interesting happens—instead of continuing to get denser, the water starts becoming less dense and rises to the surface. So, at water temperatures below 39.2 °F ( 4 °C ), the coldest water is at the surface where, in contact with the frigid air, it continues to get colder, and eventually forms a skin of surface ice when it reaches 32 °F (0 °C); freezing point. The ice thickens as deeper water reaches freezing point. But ice formation is always from the top down.

Streams don’t freeze because their water is turbulent and the cold surface is constantly mixing with the warmer water below. So, the agitated water in streams doesn’t form ice until the entire depth reaches the freezing point. But it certainly can freeze and eventually will - as long as the air temperature stays cold enough long enough. When constantly mixing water does eventually freeze it forms a special ice called “frazil ice” that forms not just at the surface, but throughout the water.

So turbulent water freezes more slowly. But the thought that a few ping-pong balls drifting around the surface of a water pan can create the sort of turbulent mixing necessary to prevent ice formation on the surface seems like a bit of a stretch to me. To find out the truth I set up the experiment.

Materials and Methods

I poured two quarts (1.9 liters) of water drawn from my kitchen faucet into each of three plastic one-gallon (3.8 liter) ice-cream buckets. I put the buckets of water side by side on my deck and allowed the temperatures to equilibrate for a half-hour. Then I put three ping-pong balls into each of two containers. I didn’t interact with the balls in the first container, but “pecked” at the balls in the second container with my finger, mimicking the pecking action of a chicken. The third container, the control, remained free of ping-pong balls. Immediately after placing the ping-pong balls, I read the temperature just below the water surface of each container using an electronic thermometer with an accuracy rating of +/- 2 degrees, F. Every half hour I “pecked” the balls in the second container, read water temperatures, and visually checked for ice formation.

I started the experiment at 3:30 PM and continued until every container had a solid layer of ice over its surface. The display from my phone’s weather app shows the temperature and wind conditions for the duration of the experiment. In spite of the near absence of wind, the ping pong balls did move around the “unpecked” container, until they froze in place, as can be seen in the photographs. Maybe their movement was caused by disturbance to the water by the act of putting the thermometer probe in the water every half-hour.

Results

Beginning of experiment (0 hours):
Unpecked temp. = 49.0° F; Pecked temp. = 49.4° F; Control = 50.0° F; Thermometer accuracy = +/- 2° F.

0.5 hour:
Unpecked temp. = 47.6° F; Pecked temp. = 47.7° F; Control = 47.3° F; Thermometer accuracy = +/- 2° F.

1 hour:
Unpecked temp. = 40.6° F; Pecked temp. = 41.1° F; Control = 41.1° F; Thermometer accuracy = +/- 2° F.

1.5 hours:
Paper thin ice on the “unpecked” container.
Unpecked temp. = 36.3° F; Pecked temp. = 35.7° F; Control = 37.5° F; Thermometer accuracy = +/- 2° F.

2 hours:
Thin ice on all three containers.
Unpecked temp. = 32.40° F; Pecked temp. = 32.5° F; Control = 32.7° F; Thermometer accuracy = +/- 2° F.

2.5 hours:
I was unable to read temperatures. I couldn’t insert the thermometer probe into the water because of solid ice on all three containers.

Discussion

All three water containers started with liquid water at a temperature around 49.5 at the beginning of the experiment. At the end of the experiment, 2.5 hours later, all three containers were covered with a solid sheet of ice. While one container containing ping-pong balls was observed to form ice slightly before the other two. all three containers cooled at a similar rate.

Conclusion

This experiment has demonstrated that ping-pong balls placed on top of water containers don’t slow the rate of ice formation.

Ping-pong balls are great for playing ping-pong.
Ping-pong balls are great for playing beer pong, if you’re into that sort of thing.
Ping-pong balls are not so great for keeping the water in your coop from freezing.
Science rocks!

Of course, the validation of any scientific experiment is the ability of other researchers in other settings to replicate the results. So, if you’d like to do some science, try this experiment at your house and then let me know how it worked for you!