If algae threatens to throttle your favourite spitting frog, or your fountain begins to ooze rather than splash, the following guide can help you diagnose and solve the problem.
Consistent, gradual water loss
• Evaporation: ponds can lose up to five centimetres of water per week in really hot, dry spells.
• Over-spraying: waterfalls and fountains may overshoot their boundaries.
• Leaking supply pipe. Note: A leak in the pond itself is the least likely reason for this type of water loss, according to landscape architect Dean Woolley, owner of Milton, Ontario-based Waterwerx. “But it's the major perceived threat among pond owners,” he says.
• Keep your pond topped up manually or install an automatic fill system (and check to be sure that it's functioning properly).
• Adjust fountains or waterfalls.
• Check outside water supply pipes for leaks; make sure clamps are tight.
Irregular water loss
CAUSE: Diverted water pools up to a certain point and then spills over (a shift in rocks can create an area where water collects, then overflows).
• Make sure rocks and liner are still in their original positions.
• Correct any diversion.
Catastrophic water loss
SOLUTION: In early spring, or for a new pond, wait until the water stops draining; then look for a hole or crack at that level (check under any folds in the liner). If the source of the leak is not apparent, scrub the liner for a better view. Apply a patch, using the same material as the liner. Properly applied, a patch should last the lifetime of the liner.
CAUSE: Temperature changes, runoff, heavy rain and/or snow-melt that allow single cell algae to flourish.
• Wait four to six weeks to let new plant growth compete with the algae for nutrients.
• If plants aren't catching up and checking algae growth, add hardy, oxygenating plants early next spring. • Aim for 50 to 70 per cent plant coverage of the water surface to prevent sunlight from reaching algae spores.
• Chemical algicides are available but must be used correctly to avoid harming fish and plant life; follow label directions. Or add beneficial bacteria and naturally occurring enzymes (available at garden centres and pond supply stores) that promote decomposition and break down sludge, discouraging the nutrients that feed algae.
• Use ultraviolet clarifiers (free-floating algae pass beneath a UV lamp and are killed), which are available at pond supply stores.