One of the disadvantages of caring for a smaller pond [ours is 500 US gallons (2,000 litres)], is that it is more prone to contamination from rotting vegetation, both from the water plants themselves, and from leaves blowing in the the fall and early winter months. Rotting vegetation produces a foul odour, clouds the water, and eats up the available oxygen. While a larger pond, especially one with water flow in and out of it, may be able to "absorb" a considerable amount of natural contamination, the small ones simply cannot.

Last winter we thought we would try not covering the pond in the usual manner to see if we could speed up spring a bit. A folly! We ended up having a winter which would not begin (first snow to stay was in January), and leaves continued to fall until mid December. Needless to say, spring was late, the pond thawed the same time it normally does, and the pond was full of leaves! Also we had added water hyacinth the previous summer which dropped an enormous amount of its black root structure over the growing season. The combination was potent indeed.

First things first! Since we have a short stream which runs to the pond, then falls to the water level, we had to remove the rocks from the upper part and thoroughly flush out the stream bed.

We run the pond and waterfall with a small inexpensive sump pump (under $100 Canadian, $70 US), with a common garden hose splitter to control water volume. Convenient for this kind of situation, since all you have to do is attach the garden hose and empty the pond onto the dryest part of your garden. (the odour dissipates rapidly!) and the water is not wasted.

After discovering the water hyacinth roots were clogging the sump pump last summer, we started putting the pump into a large plastic container (15" dia.) normally used for planting water lilies and the like, to separate the pump from the bottom "sludge". This allows us to easily pump out to the level of the top of the container while spraying down the pots and sides of the pond before beginning to remove the leaves and other debris with a net.

The next step has two schools of thought. There are those who get in with sponges and brushes, even mild cleansers (dish soap only! please) to remove every spot of visible algae growth. (I have to be careful here, I live with one of these mildly retentive individuals!) The truth is the moment you de-clorinate the water the zillions of algae you DRINK every day start reproducing - so, why bother killing the ones already there? Anyway, if you have a good balance of the water surface covered with plants, under water oxygenators, and fish to eat the algae that does grow, then the pond water will remain relatively clear in the northern climate summer months. I look upon the algae coating the pond liner as a friend, fish food starter!
 
Draining the pond also gives you the opportunity to examine the state of your pond liner. Most are guaranteed for 10 years, and will in reality last much longer if not exposed to too much UV. However, remember that sharp rock you managed to kick in last summer! - sharp rocks, whether falling in or rising up under the liner are the number one cause of liner leaks. There are a number of reliable patch kits available, including ones which work under water. However, it it much easier to do repairs with the pond drained - and yes, now you do have to clean off the algae!

Secondly, it also a good time to see whether it is time to re-pot your water plants. In general terms, every three years is likely. The large rhizome ones, like water lilies, if planted

in plastic pots may even have begun to deform the pot (red arrows & inset - picture below). Repotting before they begin to actively grow is the proper time, although with sufficient care, it can be done later.

Dividing makes more sense than potting up if the plants you had last season grew to the size you wanted. Planting is simple. Use pots or tubs without drainage holes, a heavy clay soil with no humus or soil lighteners, plant shallowly, and firm in thoroughly. Cover the surface with pebbles or crushed rock to prevent the soil from being disturbed by the fish, and saturate before plunging back into the water.

Third, you can at the same time of course easily move the pots from their winter location at the bottom of the pond to the shelf level, if required, and add fertilizer tabs. Summer is busy for us, so we prefer the "all season" variety, as opposed to the monthly ones. Both are simple to use, but follow the directions in regards to depth - feeding the algae is counter-productive!


And finally, fill the pond back up taking care to use a reliable chlorine and cloramine remover. There are many available on the market, but search out ones specifically for outdoor ponds - they come in higher concentrations and end up being much cheaper than those intended for aquarium use. Laguna is one brand available in Canada you can look for.

And now, with the sound of trickling water filling your head, you can put your feet up and dream of lily blossoms. Don't be alarmed if after a few days, the water clouds - the algae bloom will disappear as your plants grow, fish are re-introduced and the natural balance of algae and flora and fauna re-establishes itself. I should note that this "natural" approach to pond maintenance is possible only if you have dug your pond to a depth capable of over-wintering your water plants. A shallow pond, even in a northern climate, heats up too much to restrain the consequential growth of algae. In such circumstances, you will have to resort to a biofilter of some sort to add to the "anti-algae" side of the equation!

However - and this is the greatest advantage of water gardening - once you have achieved a workable balance in your pond, there is little work you have to do until fall arrives, and you need to put it to bed along with the rest of your garden!