Pond Water Maintenance

PROBLEM

POSSIBLE CAUSES

SOLUTIONS

Excessive algae

Too little competition

Introduce other plants to keep algae from gobbling up all the oxygen and nutrients.

Too much sunlight

Algae thrives on sunlight that reaches underwater; add floating plants like water lilies to help shade the bottom.

Too many nutrients

Don't use regular potting soil or fertilizers for pond plants; they leach excessive nutrients into the water. Instead, use soil especially made for aquatic gardens and slow-release aquatic plant food.

Cloudy, brown water

Pump and filter not working efficiently

Regularly clean the pond filter (as often as weekly in summer). For a foam filter, remove it, wash with water and liquid detergent, squeeze it out and replace; for a cartridge filter, hose it down with a strong stream. Several times a season, clean inside filter pipes with a small brush.

Too much algae

Follow steps for "Excessive algae," above.

Leaves and plant debris in pond

Dead leaves from nearby trees

Skim pond surface regularly with a net on a long pole. If you have several trees very close to the pond, catch leaves in fall by stretching garden netting all the way across pond surface and anchoring it on both sides.

Dead leaves from pond plants

Frequently examine pond plants and remove any yellowing or dying leaves.

Floating plants appear unhealthy

Plants have outgrown container

When a plant such as a water lily has excessive leaf growth, with leaves rising above the water surface, it probably isn't getting enough nutrients from its container to promote blooming. Remove the plant from the container, divide it, and put half of it in a second container elsewhere in the pond.

Unhealthy or dying pond fish

Lack of oxygen

Add more submerged oxygenating plants like duckweed and eel grass. Reducing amount of algae will also help.

Overpopulation

A general rule is to have 1 to 2 inches (2.5 to 5 cm) of fish length for each square foot (929 square cm) of pond. For example, in a 60-squarefoot (5.5-square-m) pond, 15 fish 4 inches (10 cm) long is acceptable, and 30 fish is an absolute maximum.

Too much chlorine or chloramine in the water

Both of these are deadly to fish. A pool store will have kits to test for these chemicals, and also commercial treatments to reduce them to a safe level.

Plants or fish frozen under ice

Winter

Move fish and container plants that are not winter-hardy to a sheltered place. To provide oxygen and air circulation for the remaining fish and plants, leave a large plastic ball on the surface all winter; its motion will keep a section of the pond unfrozen. You can also create an airspace between ice and water by melting a small hole in the ice and siphoning out some water. Do NOT create a hole by tapping the ice because doing so would be bad for the fish

Dense, matted underwater plants

Excessive growth of submerged plants

Once or twice a season, thin out submerged plants; divide them if necessary.

Low water level

Evaporation, particularly in hot weather

Check water daily in summer; top off with a hose as needed.

Leak in pond liner or fiberglass form

Repair tears in a pond liner with a patch made from a scrap of liner attached by epoxy. Fix cracks in a rigid pond form with a fiberglass-repair kit. Your only chance to find submerged leaks is when you empty the pond--which should happen only once every few years--so be sure to check the entire pond thoroughly at that time.