How do I control algae in a water feature?

Algae in water features is primarily caused by excess nutrients, sunlight, and poor water circulation — controlling these three factors will dramatically reduce algae growth in New Brunswick's humid climate.

Algae thrives in New Brunswick's warm, humid summers, especially in still water with high nutrient levels. The key to control is understanding that algae needs three things: sunlight, nutrients, and stagnant water. Remove or reduce any of these, and you'll see significant improvement.

Water circulation and aeration are your most powerful tools. Install a pump that circulates the entire volume of your water feature at least once every two hours. Moving water prevents algae from establishing and increases oxygen levels that beneficial bacteria need to break down organic waste. In smaller features like fountains, ensure the pump runs continuously during growing season (May through September in NB). For larger ponds, consider adding an aerator or waterfall feature.

Nutrient management requires removing the food source algae feeds on. This means regularly removing fallen leaves, dead plant material, and fish waste if you have aquatic life. In New Brunswick's deciduous forests, leaf drop in October can quickly overwhelm a water feature if not managed. Install a skimmer or net to catch debris before it decomposes. Avoid over-fertilizing nearby garden beds, as runoff feeds algae growth.

Sunlight control through strategic placement and plant coverage helps significantly. If possible, locate water features where they receive morning sun but afternoon shade. Add floating plants like water lilies that cover 50-70% of the surface — they compete directly with algae for nutrients while providing shade. Submerged plants like hornwort act as natural filters, absorbing nutrients before algae can use them.

Natural treatments work well for maintenance. Beneficial bacteria products help establish healthy microorganisms that compete with algae. Barley straw extract releases compounds that inhibit algae growth as it decomposes — add it in spring before algae season begins. For immediate results, UV sterilizers kill algae as water passes through, though they require regular bulb replacement.

Chemical treatments should be your last resort and require careful application. Algaecides work quickly but can harm fish and beneficial plants if overused. Always follow label directions precisely and ensure products are safe for any aquatic life. In New Brunswick's variable spring weather, avoid treatments when temperatures fluctuate dramatically, as stressed aquatic life is more sensitive to chemicals.

Seasonal maintenance prevents major algae blooms. In spring, clean out accumulated winter debris and restart pumps gradually as water temperatures rise above 10°C (typically late April to early May in NB). During summer's peak growing season, test water weekly and remove string algae by hand before it establishes. In fall, reduce feeding if you have fish, and consider covering smaller features to prevent leaf accumulation.

When to hire a professional: Large pond installations, UV sterilizer setup, or persistent algae problems despite following these steps often require expert diagnosis. A landscaper experienced with water features can assess circulation patterns, recommend appropriate equipment sizing, and identify specific algae types that might need targeted treatment.

Need help finding a landscaper experienced with water features? New Brunswick Landscaping can match you with local professionals who understand our Maritime climate's unique challenges for water feature maintenance.