Some Thoughts on a 16-Year-Old Windowsill Aquarium

While doing research for a previous blog post, I happened upon an article published in Thomas Gill’s 1827 “The Technology Repository: Containing Practical Information of Subjects Connected with Discoveries and Improvements in Useful Arts” on how to establish a windowsill aquarium (1). Gill’s article was of interest to me because I have been keeping a windowsill aquarium since April, 2008. With this month being my aquarium’s 16th anniversary, I wanted to share with readers how it came to be and what I learned from Gill and others about starting and maintaining a windowsill aquarium.

Why keep a windowsill aquarium? Well, in 2008, Hooke College of Applied Sciences offered its first microscopy workshop, called Microscopy Camp, for middle school and high school science teachers. Over a week’s time, students performed a wide variety of microscopical experiments they could use in their classroom, some of which required microscopical pond life. To have plenty of pond water on hand, our Scientific Advisor, John Gustav Delly, helped me establish a windowsill aquarium.

John collected water from a pond at the Old School Forest Preserve in Libertyville, Illinois. He also gathered a few small aquatic plants and gravel from the pond. All of the contents were deposited into a six-inch diameter cylindrical glass battery jar and labeled with the location and date of establishment. The aquarium was then placed on the windowsill in my office.

Experiment 19

For our Microscopy Camp, John had also written a book titled “Microscopy Experiments Featuring the Boreal/Motic Microscope” to be used by the students for the course. The book, which is now available on our website, contains 36 microscopy experiments including Experiment 19, which describes how to go about creating your own micro-aquarium to use with a microscope. Below is a portion of the experiment’s description.

“A trough is a kind of miniature aquarium that can be used for the microscopical observation and study of various mini ecosystems. The trough differs from a live box or well slide in that it is exposed at the top, not covered with a piece of glass. This allows the additional study of floating plants, surface-dwelling organisms, mosquito larvae, etc…”

An example of a finished miniature aquarium filled with the pond water from the windowsill aquarium and its intended use with a student microscope are pictured below.

Does it Smell Bad?

A couple of windowsill aquaria can be seen in the 2008 Microscopy Camp class photo below. The one from my office is indicated by the yellow arrow. Notice how clear the pond water is after being established about eight weeks before this photograph was taken.

With age, the aquarium has morphed into a mass of dense algae growing along the tank’s glass walls. When people come into my office and notice this unruly-looking green growth they ask, “Does it smell bad?” To which I reply, “It smells a little bit like dirt.”

My office window faces south, and from the above figures you can see the side facing the sun has turned the algae a sort of orange color. This coloration is from exposure to strong sunlight, associated with the accumulation of xanthophyll pigments.

Just Add Water?

I always thought of my windowsill aquarium as the ideal houseplant, only requiring water every few weeks—when the water level dropped, it was easily restored by simply adding some tap water. As the years passed, I noticed a few changes in the type of micro-organisms dashing about when viewed with the microscope. Organisms such as daphnia were now few and far between, but vorticellae, paramecia, and an abundance of water mites, were alive and well.

In looking at the dense algae growing in the aquarium, I began to wonder if there was an ideal way to maintain it? The answer is yes, but like most things in life, there are different schools of thought.

Starting with the Basics

To find out how the pros maintain a windowsill aquarium, I began reading bits and pieces of books and articles with a particular focus on older publications. Since I was already familiar with Gill’s articles from his 1827 “The Technology Repository: Containing Practical Information of Subjects Connected with Discoveries and Improvements in Useful Arts”, I began there. Gill’s initial set up of a windowsill aquarium reminded me of the one Delly established in 2008. From Gill’s 1827 publication:

“The Editor, in June last, brought home from a pond in the neighbourhood of this metropolis, a bottle containing water abounding in animalcula, and having plenty of…duck-weed floating upon its surface. This he put in a vessel of white earthen ware…placed on the cill outside of a window, and ever since it has afforded him a never-failing supply of living and most entertaining objects for his microscope.”

Gill’s practice of leaving the windowsill aquarium outside in the elements was a bit of a curveball, but I can see how that would be a more natural setting as compared to keeping it indoors.

As the months passed from June to October, Gill gives the reader an update on his windowsill aquarium:

“…in the end of October, but few of the leaves (duckweed) themselves have preserved their green color, they having, by continual consumption of the animalcula, to which they afford food, now become transparent…”

Gill describes removing one of the transparent leaves using a feather from a crow’s quill and placing a portion of it on a microscope slide, which has been modified with finely drawn-out lines of red sealing wax deposited on the slide to create a “shallow kind of pond” for viewing the microorganisms that have taken up residency within the remaining portions of the decomposed leaf.

Wintering with the Microscope

Alfred Stokes, in his 1889 article To Make a Microscopical Aquarium for Winter Use gives us another reason for starting a windowsill aquarium along with a few maintenance tips. He encourages the reader to establish a microscopical aquarium as another form of entertainment during the cold days of winter:

“…the water supplies an endless variety, and even the winter need not chill the microscopist’s ardor.”
Stokes goes on to describe an almost therapeutic benefit of establishing a windowsill aquarium for those unable to leave their home or who live in an urban setting.

“Some are confined to their chambers by bodily ailments, some are forced to reside within the very heart of some great city, without opportunities of breathing the fresh country air more than a few times in the course of a year: and yet there is not one who may not find an endless series of common objects for his microscope within the limits of the tiniest chamber.”

He later warns the reader of “an enemy of the microscopical aquarium”, the water snail, but provides advice on how to eradicate them from your aquarium.

Tanks for the Microscope

The book “Modern Microscopy“ by M. I. Cross and Martin Cole (Fifth Edition, 1922 printing) contains several newly-published topics that did not appear in previous editions, one being a section titled Pond Life. In this new section, Cross and Cole describe the basics of keeping a windowsill aquarium, but also take setting up an aquarium to a much higher level:

“For keeping microscopic life, I have found no difference between large and small aquaria, but small tanks are the more manageable…the great thing to be attended is the proper aeration with plants…and not to overstock the tank with either animal of vegetable life.”

I took note of Cross’ and Cole’s advice, as my windowsill aquarium might qualify as having an overstock of vegetable/algae life.

Their approach soon becomes more involved as compared to Gill’s and Stokes’ setups, requiring multiple aquaria and the separation of the collected pond water.

“On reaching home, the first thing to do is empty the collecting-bottles into small aquaria so that the captures may be critically examined, isolated, and, if found desirable, placed under the microscope. By far the best and most convenient way of doing this is to transfer the contents of each bottle into a small window aquarium, filling it up with tap-water. The weeds and rootlets that have been brought home are put in another window aquarium in clean pond-water.”

One reason Cross and Cole go to such lengths to establish each windowsill aquarium is because of their eventual study, using what they call a “tank microscope”, pictured below.

The flat rectangular shape of the aquarium allows the life within the tank to be studied using a microscope objective attached to an articulating arm. They remark that one of their tanks has been in constant use for over twelve years, and that using a round aquarium is a no-no:

“In round bottles it is very difficult to see minute animals clearly…The difficulty of seeing and capturing small objects in a large or ordinary round aquarium is very great, and the use of a pocket lens almost hopeless…”

In my own experience, I’ve found inverting a 10X microscope eyepiece and placing it up against the glass of my round aquarium provides an opportunity to view some of the larger forms of life such as the water mites. I did not feel that the curvature of my tank was much of a problem, but of course a flat one would be ideal.

Taking a Little Off the Top

Per Cross’ and Cole’s recommendation, I went ahead and began thinning out the algae. To me it was like giving my windowsill aquarium a haircut; just like your hair, you know the algae, too, will soon grow back.

To remove the algae, I began cutting it with a knife in a vertical direction, perpendicular to the aquarium’s bottom; I concentrated on clearing out most of the orange algae and placed it on a tray. Noticing the weight of the algae when I picked up the tray, I decided to put the entire contents on a scale. The wet algae weighed in at just over two pounds!

Topping Off the Tank

Cross and Cole also recommended occasionally replenishing the water supply from the original source:

“Though the spring and autumn are perhaps the best season for collecting, pond-life is never absent, even in the winter under the ice…On the whole, the best plan is to go out and collect a fresh supply from time to time…”

I returned to the Old School Forest Preserve where Delly had collected the original pond water sample 16 years prior and replenished the supply. Using a stainless steel soup ladle, I collected some of the pond water, placed it in a large plastic container, and brought it back to the office.

In an interesting aside, I discovered that M. I. Cross’s name is a pseudonym for Fredrich William Watson-Baker. This bit of information is referenced in The Microscope Journal, January-February 1953.

“The lamented death early in 1952, of erstwhile head of the firm of Watson allows the writer to reveal a secret known for some time—that he was “M.I. Cross,” part author with M.J. Cole of the well-known book. At the writer’s request, a friend of the family approached him on the subject and was told that he preferred the secret to be kept during his lifetime.”

Watson-Baker’s tongue-in-cheek pseudonym M.I. Cross nearly spells out the word microscope.

This Old Windowsill Aquarium

With the algae thinned and new pond water added, my windowsill aquarium was restored and looking more like the original established 16 years ago. Many of the old inhabitants were still dashing around when placed under the microscope, and a few new faces were now present.

I will leave you with one last quote from Alfred Stokes regarding establishing your own windowsill aquarium:

“There are many complex devices afforded to facilitate this object, all of which may be commendable for their special purposes, but the simpler the device the better are the results…”

I agree with Stokes—the simpler the better. There are best practices to follow, but there is no single correct way to establish a windowsill aquarium, and the maintenance of the aquarium is not an exact science, either. Your windowsill aquarium will certainly change over time and that’s the fun of it.

References

1. Gill, Thomas, (1829). The Technology Repository: Containing Practical Information of Subjects Connected with Discoveries and Improvements in Useful Arts, London, T. Cadell Strand.
2. Stokes, Alfred. The Microscope: An Illustrated Monthly Journal Devoted to Microscopical Sciences, Vol IX, No. 10, October 1889.
3. Cross, M.I. and Cole, M. (1922). Modern Microscopy, Fifth Edition, 1922.
4. Baron, Arthur (Editor). The Microscope: The British Journal of Microscopy and Photomicrography, Vol. 9, No. 5, January-February 1953.