IN MORE THAN 25 YEARS of operating two homemade in-ground water gardens, I have probably broken lots of rules—especially about winterizing. But there are some rules I never break, and keeping the surfaces from freezing over is the most important one of all.
If trapped under a solid sheet of ice, decomposing plant material and wastes from fish or other inhabitants can create a building of noxious elements such as ammonia, nitrites and carbon dioxide, all of which can harm (or suffocate) any life overwintering in the pool, and also taint the water.
Make a plan now to keep a hole in the ice; never let the pool freeze completely over. Depending on the pool size and your wintertime lows, maintain at least a small hole in the ice with an appropriate wattage level of floating pond de-icer (that’s one of mine, above; there are many styles and sizes). Water-garden suppliers can help you choose the correct de-icer.
Some water gardeners use a bubbler, or aerator, operated by a pump and submerged maybe 6 inches and positioned near the edge of the pool, to keep a hole open; that doesn’t work here in a harsh winter, but may for you. In early spring, before I pull the de-icer, the frogs act as if it’s a float to sunbathe on (below). All winter long, the birds thank me for supplying water as a side-effect of my de-icing scheme.
I am in a cold-winter zone, so I turn off my pumps around Thanksgiving, meaning the spillways and biological filters are no longer operational. I don’t pull my pumps (some experts recommend it), but what turning off the water does is protect tubing–much of it is exterior to the pool–from freezing, then perhaps rupturing during thaws. I do lift, empty and clean external filters (because they, too, would freeze and crack).
I don’t drain or clean my pools in fall or spring specifically, however, or actually anytime, but work all season long to maintain a healthy water condition instead—going on that “an ounce of prevention” mantra.
Most helpful tools on that score: plenty of submerged oxygenator plants such as perennial parrot feather (Myriophyllum) and anacharis (Elodea), and also floating ones that shade the surface (helping limit algae growth). The parrot feather (seen, above, just starting to poke through the surface in late spring), which is perennial in my small pools even here in Zone 5, does some shading once it starts to fill in. I also love the dainty little true floaters such as Azolla and Lemna (covering the pool in the above photo). Note: Never put any aquatic plant into natural waterways; they are only for use in lined water gardens and pots.
In fall I trim any that are up and over the edge, and thin somewhat if the pool seems congested. (Non-hardy plants must be removed before frost, and stored or discarded.)
Using a net or skimmer, I also remove leaves that blow in regularly, especially in fall, and use biological (non-chemical) additives spring and summer to stimulate the decomposition of pond debris. These are helpful bacteria, specifically. Note: I don’t strive for the bottoms of the pools to be muck-free, however; my amphibian friends love a nice cushion of glop down there to sleep on, or in. Though my pools are just 1,800 and 800 gallons, several frog species and two salamander species reproduce in them year after year. Amazing, and a wonder I never tire of celebrating.
And if you have seasonal water gardens in pots—remember mine, above, by the kitchen door?—be sure to empty and store them if the container’s not weatherproof. But you probably already figured that part out.
got fish? stop feeding
ONCE THE WATER is below about 50 degrees, I don’t feed the comets (very hardy goldfish-like creatures) who have lived for many years in one pool. They do fine without supplemental food pellets until spring. My fish actually tell me around October that they are done eating; even if I toss pellets into the pool, they show disinterest once it’s cold.