Southwestern USA
Get your pond ready for a long and rewarding summer!

Spring Pond Activities

by Leo Martin, Phoenix, Arizona

Here in Phoenix temperatures have been in the 80s F (27-31 C) for several weeks, and it hit 90° F (32-36° C) today. Very soon 100s F (38-42 C) will arrive. Now is an excellent time to ready the pond for a long and rewarding summer. Two weeks ago would have been an even better time to begin.

My pond measures about 6 feet (2 meters) wide, 12 feet (3.7 meters) long, and 4 feet (1.3 meters) deep, built of concrete block walls with a concrete slab bottom. Two feet (0.6 meters) of the pond wall rises above ground level. Resting on top of the concrete block walls, a redwood shelf/bench allows human closeness to fragrant waterlilies. I clean, sand, and restain this bench about every three years, taking care to keep fish-toxic stain out of the pond.

Fiberglass fabric and resin adhere to the concrete-block-pond's interior walls, making them waterproof. My pond has no plumbing. The bottom slopes to one corner to allow easy draining by a sump pump. An outside pond corner contains an electrical outlet to power my pump (and whatever else). The line has the code-required ground-fault interruptor for safety. Electric codes typically require an electrical outlet to be at least six feet (two meters) from a pond. I do not use pond lights.

A water line runs to the pond. The line includes a backflow preventer and a manual valve coming off the main household water line. I use a fairly large underwater pump to set up a circular, bottom-to-top underwater current in my pond. The circulation keeps the water well mixed, thereby avoiding strong temperature zones and deoxygenated zones near the bottom. The pump operates constantly during warm weather to keep the water blended. I do not have a filter; I can't imagine a pond as large as mine and kept in balance would ever need a filter so long as the water circulates constantly.

During our mild Phonix winters, while there is little to see in the pond, I place plastic greenhouse shelving across my pond to support many pots of winter-growing bulbs and succulents. The pond generously provides a beneficial heat source that prevents the seedling pots from freezing during our occasional frosty nights. These winter-growers are going dormant now for the summer. I remove these plants and place them in their summer homes. Then I move the shelving to another part of my garden and prepare it for summer seed planting. Now I really get down to cleaning the pond.

Begin at the Top

First, I remove all the hair algae which completely covers my pond. I try to salvage cabomba poking through here and there, but what remains submerged grows so fast in warm water that losing some of it presents no problem. I use removed hair algae to mulch my citrus trees. I find that my dogs enjoy eating the algae, so I take care where I put the globs from the pond.

To Drain

Next, I decide whether or not to drain and refill my pond. I base the decision on dissolved solids in my water, and how profusely my waterlilies grew last season. If no line of mineral buildup exists on the edges of the pond, and if the waterlilies grow nicely, I drain my pond about every five years. If I notice mineral buildup, or if the lilies aren't growing as expected despite good fertilizing, I drain and refill my pond. I never drain my pond yearly; I find it useless and also see it as too wasteful of our precious water. Besides, it is quite easy to clean a filled pond.

When draining my pond, I use a garden hose from the sump pump for watering my citrus trees. Here in the desert I never waste water by pumping it to a drain in the street. When the water level gets quite low, I carefully net the fish and immediately transfer them to a prepared storage tank.

As the water level drops, I remove plants in pots -- which normally sit on 8 inch (0.2 meter) by 8 inch by 16 inch (0.4 meter) concrete blocks -- to a shady area for temporary storage. I protect sprouting plant foliage with a damp newspaper covering. The pots remain there only a day or so, and I repot all my plants every year. Floating plants wait patiently in a prepared tank.

If You Can Reach It, Clean It

Once drained, I remove the supporting concrete blocks, scoop out all the soil that has fallen from the pots onto the pond bottom, and give the pond liner and concrete block supports a good scrubbing with a plastic brush. I use soap and water to clean first the sides, then the bottom, as well as possible. I then rinse completely, several times, pumping the water to my orchard. Mild soap doesn't hurt trees.

If I think my pond has a leak, I apply a fresh coat or two of fiberglass resin. If I had a different kind of pond lining I would inspect it very closely and fix any problem. Now is also the time to clean fountain heads, lights, and pumps. A solution of 1/2 cup (0.24 liter) vinegar in a gallon (4 liters) of water works effectively as an overnight soak to remove mineral deposits from equipment and pond liners. Usually some scrubbing is needed, too. I don't use strong demineralizers. If I don't rinse thoroughly enough, a little vinegar doesn't hurt anything in the pond, but phosphoric acid might.


Upon refilling the pond about halfway, I set the concrete block supports on the edge of the pond. They are easier to manipulate under water than in an empty pond. I climb into the pond and lift the supports into place, taking care not to drag concrete blocks on the liner. I am strong enough to handle these blocks on my own; but if I were not, I would be sure to have a helper around, or I would use twice as many 8" (0.2 meters) x 8" x 8" blocks. I don't use gloves when handling the block but many people would want to since it does roughen up your hands.

I fill the pond about 3/4 full, then set the repotted waterlilies, and all else that goes on the blocks in the pond. To avoid overflowing and wasting water, I don't fill the pond to the final level until everything that belongs in it is there. I put my recirculating pump back in, connect it, and run overnight. This oxygenates the water, and allows it warm to ambient temperature. My tap water is fine for fish and plants. If yours isn't, you might want to adjust the chemistry now, before putting fish back into the pond. The next day, I return the fish to the pond.

. . . Or Not to Drain

If I don't drain my pond, I still remove all the plants, one by one, and repot them. I remove the pump, my simple glazed ceramic sphere fountain with silicone water tubing that I assembled myself, my tasteless Talavera ceramic frog planter that makes everybody think I am a child of the 1960s, and my underwater hoses, and clean them. I use a siphon to remove as much stuff as posible from the pond bottom.

Repotting Plants

Read about repotting plants on the Victoria-Adventure site. All I say is, "Do it every year!" The first flush of growth responds so much better with a huge load of fertilizer lurking four inches below the soil surface. (Very old gardening books suggest that proper gardeners bury trapped rodent carcasses in waterlily and lotus pots, though I don't recommend this procedure.) I re-use the same soil each year; I can't tell the difference by replacing it. Other people recommend using fresh soil with each repotting. I use my local soil, decomposed granite, for my plants.

Through a Pond Darkly

If you drain and refill, your pond looks like a bathtub for a few days. If you don't drain, but clean it up, the water looks very clear this time of year. Just wait!

Lilies haven't covered the surface. You have taken out all the hair algae. Plenty of sun warms the water making its temperature rise. One day soon you step outside and notice your pond filled with an opaque green soup of microscopic floating algae. Floating algae need water, light, nutrients, and warmth. They cause the cloudy water. When you remove one--or better yet, two or three--of their requirements, your water clears up. Without filtering, and without chemicals.

In the winter it is usually too cold, even in Phoenix, for floating algae to flourish. But we don't have much control over summer water temperatures in outdoor ponds, and in any case, we want warm water because it makes waterlilies bloom better. When lilies eventually grow and cover enough of the pond, they screen out the sun and end the pea soup stage. But this takes several weeks in warm weather.

Hair algae is your friend here. Hair algae scavenges nutrients from the water so efficiently that it starves the floating algae. Hair algal spores grow on your plants, and in the air, too. So -- to easily treat against pea soup pond conditions you simply wait as the hair algae grow. You might want to remove them when they mat on the water surface, but allow them on the sides of your pond and on the plant containers.

After encouraging a nice coating of hair algae on the underwater surfaces of your pond, one day you will walk outside and overnight your pond has become crystal clear. Really. I promise. Please just wait patiently; don't pour this or that algae killer into your pond. Given time, hair algae really turns your water as clear as glass.

Sit Back, Wait, and Enjoy

You have done your part. You've been patient. Now the weather and your plants interact. Soon you have a beautiful pond for another summer season. Ponds develop each spring as do plants arising gradually from winter slumber. Enjoy the spring unfolding of your pond.

Next time - Why I chose fiberglass lining and how I did it myself.



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