Green Water, Cloudy Water - What should I Do?

When a pond is first set up the water is crystal clear.  As fish and plants are introduced into the pond, almost instantly a serene and natural-looking environment is created.  Over time however, water can become murky.  The murky conditions can be caused by suspended sediment or algae blooms.  

In the springtime we often will repot our pond plants and fertilize our plants, move our pots from last year to a new location in the pond, or even add new plant varieties to our ponds.  In the spring we will re-establish our filters, skimmers, and waterfalls.  Spring is a great time to remove any materials such as leaves or sticks that fallen into our pond from the winter months.  These activities can cause the water to become murky and stir up nutrients as well.

We will take a look at how these activities can be a concern and describe methods for the best course of action.  

Algae blooms appear as pea-green soup or filamentous mats that float to the surface.  Algae blooms develop when there is an excessive amount of nutrients.  This usually occurs in the spring prior to plant growth or anytime there is excess nutrients in the water.  Excessive phosphate and nitrate are two of the major components contributing to algae growth.  These nutrients can come from tap water, rain runoff, fish waste and debris.  A proper balance in your pond between fish and aquatic plants will help your pond water stay clear, depriving the algae of excessive nutrients.  Many blue-green algae species - Anabaena, Aphanizomenon, Gleotrichia, and Nostoc species respond to the excess phosphate in the water leading to algal problems in the pond. Therefore, the reduction of phosphate is essential to control algae blooms.  

If algae do not obtain adequate sunlight it cannot grow.  The growth of plants that cover the surface will reduce sunlight and uptake nutrients helping to inhibit algae growth.  It takes time for the plants to return to their summertime beauty.  It is advised to have at least 50% of your pond surface covered with plants to block sunlight, provide areas for the fish to swim and frolic and provide beauty to your pond.  Plant growth takes time and we must have patience for nature to work.  In the meantime, you do have methods to keep your pond free of green water if you desire.


To control algae in ponds while waiting for the plants to grow is API ALGAE CURE. API ALGAE CURE rapidly controls green water by clumping together algae, causing algae to drop out of solution. It also consumes algae-promoting nutrients to help prevent future algae growth, keeping pond water clear, and using natural active ingredients that are safe for fish, pets and wildlife.  The selected strains of bacteria in the ALGAE CURE formula have an affinity for nutrients that fed algae, such as phosphate.  The bacteria work through competitive inhibition, meaning they outcompete the algae for nutrients.  As the plants grow and through the continued use of ALGAE CURE you can obtain the perfect balance in your ponds for crystal clear water conditions inhibiting green water.  

Another alternative for success to control algae is API BLANKETWEED CURE. It works on contact to quickly kill blanketweed algae with the power of active oxygen and no copper. It is safe for fish and plants (DO NOT apply directly to plant leaves) and includes a measuring scoop for easy dosing.  

As we reestablish our waterfalls or just have areas of the ponds where we have organic sludge or sediment build-up that we want to clean but cannot easily perform maintenance on then an alternative is available as well. API POND & WATERFALL CLEANER is a powder material that deep cleans on contact with the power of active oxygen. Simply sprinkle the powder over the area of concern and it will go to work oxidizing your pond surfaces, decorative rocks, waterfalls and more. It can be used throughout entire season as needed to maintain clean clear surfaces throughout the pond.  


Water clarity can be affected by sediment or debris that is floating in the pond from your springtime cleaning or anytime the pond is disturbed. The small particles associated with this type of problem are so fine that the filter cannot trap them. API POND ACCU-CLEAR™ simply clumps together or flocculates these tiny particles and allows them to settle to the bottom of the pond or be removed by the filter. Any organic material that drops to the bottom of your pond can then be broken down by API POND-ZYME SLUDGE DESTROYER or API POND ECOFIX. These products are enzymatic pond cleaners containing multiple types of beneficial enzyme-producing bacteria. These bacteria digest pond sludge, fish waste, and other debris in your pond. When trying to clear any cloud in your pond, make sure your pond is well aerated. POND ACCU-CLEAR can be used again as the clouds reappears until your filter has a chance to remove it and it helps keep pond filters working at maximum efficiency. API POND ACCU-CLEAR, and API POND-ZYME SLUDGE DESTROYER or API POND ECOFIX, quickly clears water and breaks down fish waste and dead algae debris that can clog pumps and filters reducing overall pond maintenance.

Browse all of our API pond products here.

Perfect Pond

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