Yes, but it works best above about 60 degrees. Below 50 degrees, your fish should not be eating much (if at all). No waste is being produced by the fish or the sluggish decomposition process.
Use the Algaefix and Ecofix together. The algae will begin to die almost immediately. Dead algae, dissolved organics, and sludge build up and reduce the oxygen concentration in the water, which kills the beneficial bacteria and encourages bad bacteria.
By digesting sludge and reducing dissolved organics, EcoFix reduces organic pollution and increases the concentration of dissolved oxygen in the water. By boosting the hard-working, sludge-digesting bacteria, EcoFix reduces pond maintenance and encourages a cleaner environment.