Tending the Urban Pond

Charles W. (Chuck) Smith

I’ve wanted a pond for years.  Fish keeping in glass tanks is great, but a pond allows you to combine fish and plants at a whole new level.  However, I don’t have a pond now and I probably never will.  My house is built on solid ledge.  So how do I explore this new frontier without blasting rock or moving the home?  I decided to try an experiment.  I would buy one of those large plastic barrels and try keeping fish on the back porch with as little technology and commitment to maintenance as possible.  Here is the journal of that experiment.

May 22: I buy a “muck bucket” at ACE Hardware for $6.  Home Depot carries them as well.  It’s about 2 feet across and 2 feet high.  The label says it holds 19 gallons, but it looks bigger.  They come in red, yellow and blue.  I buy red.  I take it home and my wife promptly declares ownership because she wants a rain barrel for the garden.  I return to the store and buy a second bucket.

May 29:  My wife is into her third rain barrel when I go to Wentworth Gardens in Dover where I buy 4 water lettuce plants and 4 dwarf hyacinths at $3 each and I drop them into the original rain barrel.  These plants are small and robust and should do well.  The salesman tells me I am buying too many plants for such a small pond, but I want plant roots to help purify the water.  This is to be a low maintenance experiment with fish surviving on low stocking numbers, healthy plants, and occasional water changes.  I avoid the water lilies (at $25) when the salesman says I should keep them out in winter and “Just keep the bubbler going so the water doesn’t freeze.”  I’m not planning on a bubbler.  I’m not planning on a filter.  This is low tech.

I’m off to a good start, so I immediately procrastinate.

June 5:  I finally put a new bucket on the back porch, fill it with water, and float the water lettuce.  Bucket and plants cost me $18 total.  It’s been a cold spring and I haven’t wanted to put the fish out this early.  I’m probably too cautious.

June 9:  I buy a bag of duck weed for $1 at the club meeting.  That night it covers the surface of my pond!  I’m going to need another bucket and my hyacinths are still in the rain barrel.

June 12:  I finally move my first fish outdoors.  After the growth contest some wag from up north said my sunfish were smaller than when I took them home 3 months earlier!  I figure they didn’t do me any good and I drop each through the duckweed (the fish I mean).

Duckweed is new to me.  I’ve seen it grow well in tanks with bubble filters, but it does not get along well with power filters such as I have in the basement.  I’m a little worried about oxygenation if the entire surface of the water is covered by weed.

I buy a second bucket and my wife gets suspicious.

The truth is I am worried.  My wife’s uncle likes to say his brother is “…too heavy for light work and too light for heavy work.”  I’m thinking the nights are too cold for tropical fish and the summer days may prove too hot for temperate species.  More than the average water temperature, I’m worried about the shifts in temperature.  The buckets are small and the water can go through some pretty severe temperature swings between the cool nights and hot days.  I think that may prove harder on fish than a consistently high or low value.  This may be the biggest problem for the urban pond.

June 16:  The sunfish are eating well.  They like the cover of the floating plants and tend to hide under the roots.  I start a second bucket and add the hyacinths.  The next day I add a Golden Wonder killifish that has lost his mate.  It takes a few days before he eats and I wonder if he’s getting live food from off the roots.

July 4:  I have not seen the sunfish for weeks - the duckweed covers the surface of the bucket.  However, when I pinch some food and place my fingers under the duck weed, I get nibbled.  They’re doing fine.

Each water lettuce has 3 or 4 young shoots with smaller plants and the hyacinths have tripled in volume.  The killie swims around like he owns the place.  This is going well.

July 10:  I should have done this sooner, but I make the first water tests of the summer.  All but one measurement is better than I would have imagined.  It’s 3:30 PM and the shadow of the house is just passing over the buckets.  The air temperature is 82°F and the water is only 76°F.  Ammonia, nitrite and nitrate are all immeasurably small!  Those plants are doing a great job and growing faster than anything in my basement tanks.   I have hard tap water, but the hardness of the water in the buckets has gone down 100 ppm.  That’s probably the work of the plants, too.  The pH of the red bucket (the killifish) is still 7.5, like the tap water, but the blue bucket (the two sunfish) is 9.0!  I do a 50% water change on both the red and the blue buckets.

I figure 4 things could have happened: (1) the water lettuce raises the pH, and plants can cause the pH to shoot up during the day in poorly buffered tank water, but I know this isn’t the case here since the red buckets are more heavily planted; (2) the tap water was very alkaline the day I filled the bucket, but it’s been rock steady since we bought the house; (3) the plastic bucket is leaching something into the water since it wasn’t made for the aquarium trade, or (4) I failed to clean the bucket when I filled it.  The red and blue buckets are made by different companies, but the smart money is on (4).  The excessive algae growth suggests that some yard product must have contaminated the bucket.  It’s amazing that the sunfish are doing great in spite of the abuse.

I get a new blue bucket, fill it, add half the water lettuce and measure the water at pH=7.5.  The next few days should tell the tail.

July 18:  It’s the plastic.  Both blue buckets now read pH=9.0.  The new bucket was ok for several days, but then the pH spiked!  I swap the new bucket for one of my wife’s red rain barrels, wash it well, and fill it with clean water.  I move the plants and two days later I move the fish when the water temperature has equalized.  I also add 3 Golden Wonders to the killie bucket to keep the lonely male company.  I put two young kribs I bought at auction into the third bucket.

The label on the suspect blue bucket reads “HOMZ Storage, Home Products International, MTTB – Metallic Blue”.  I may be wrong.  Test your buckets in advance.

August 3:  I’ve had 2 set backs.  First, my largest sunfish was dead on the back deck this morning, the obvious victim of jumping contest gone horribly wrong.  All my other fish are fine.  Second, some of the water hyacinths are turning dark and soft.  Wentworth Gardens tells me it’s due to sunburn and there is no cure but the compost pile.  However, they also tell me that they need 8-10 hours of direct sunlight each day.  I don’t understand.  The water lettuce is doing great.

September 18:  It’s turning cold and time to end the experiment.  My second sunfish has disappeared sometime during the hurricanes last month.  I never found the remains.  The last of the water hyacinths died and was put on the compost pile.  The water lettuce did great.  The killifish produced 4 fry that were swimming under the canopy of floating plants and I brought them inside to grow.  They should be easy breeder points.  The male was more brilliant gold than it had ever been in the tanks.  I don’t know if it’s the live food or if he just liked the cooler water temperatures.  I lost one of the two young kribs and found the bucket filled with tadpoles!  I didn’t expect that so late in the year.

I learned a lot from this experiment and raised questions I can’t answer.  The bottom of the buckets collected a lot of dead plant material.  That should have been expected.  The nitrate never increased in spite of doing virtually no water changes!  That was not expected and suggests a new experiment for the winter fish room.  I succeeded in breeding one of my outdoor charges, although I had originally intended to try breeding White Clouds and never did.  The water never got as warm as I expected; but the summer didn’t, either.  And those water hyacinths died and never bloomed.  Still, I’ll do it again next year and maybe breed those White Clouds in the process along with a bubble nest builder.