Pond Algae:    What is it?       How to control it

What is pond algae?

Whether you have a water garden, decorative pond, stock tank, golf course pond or lake....you probably have had slimy green water or scum on them!

What are Algae? One alga is microscopic; hundreds of millions of alga are called algae.
There are more than 30,000 varieties of algae. Algae are plants, most making their food substance through photosynthesis using daylight, water and carbon dioxide.
Algae also contains chlorophyll and produce oxygen.

Algae are essential to our waters natural ecosystem, without algae our waters would not sustain life.

Advantages of algae (yes, it does have advantages)!
Fish, microorganisms feed off algae, fish can spawn (on hair algae), absorbs ammonia nitratres and phosphates. During the day algae will provide oxygen and shade.

However, very high densities (algal blooms) of uncontrolled algae growth can discolor water, lower oxygen levels, unpleasant odors and out-compete/poison other forms of life in the pond water.

PLANKTONIC ALGAE (the most common kind)
Chlamydomonas, Chlorella, Euglena, Closterium, Anacystis SPP.
Also known as: Blue Green Algae; Pea Soup; Scum; Water Bloom; Microscopic Algae.

Algae can float freely in water, coloring it green; this Planktonic algae are microscopic and when they start to bloom (usually takes place in summer months), they give ponds a pea soup coloration.
Planktonic algae can be green, brown or red in color.
They grow in nutrient-rich water. Nutrients can be produced by fish, heavy feeding of fish, even non-toxic runoff from the landscape can throw off the balance of a pond's ecosystem. Algae will then take advantage of the imbalance and grow rapidly then die back when the nutrients are depleted. Even after dying back they can sink to the bottom of your pond and form sludge.


FILAMENTOUS ALGAE
Spirogyra; Cladophora
Also known as: Hair Algae; String Algae; Scum; Waternet; Frog Spittle; Moss

Filamentous algae begins growing in the early spring and is first noticed around the edges of the pond in shallow water. This algae look like strings or filaments, and are known as being green "hair" on rocks, sides or bottom of the pond.
As the clumps grow, they break loose from the bottom, side...and float to the top, forming dense, hair like mats on the water surface.

Pond Algae - Control

No two ponds are exactly the same, what works for one pond owner may not work for another.

Fish:

Limit the amount of fish in your pond. No more than 1 inch of fish for every square foot of pond surface.
Fish waste is a rich source of nutrients which is ideal for algae.

Aquatic Plants:

Add plants to shade the pond water and extract nutrients from the water. (Algae needs the sunlight penetration to grow).

Keep the Pond Clean:

Even though plants are beneficial, if their dead leaves aren't trimmed they become a nutrient source for algae.
You can use a fish net to collect leaves from the bottom and cover the pond with a net in the Autumn before the trees lose their leaves.
Getting Rid of Sludge: Aquatic plant, tree leaves and the Planktonic algae that died and sank to the bottom, all forming sludge.
There are numerous products available for removing sludge from ponds.

Aeration:

Decomposing waste, excess fish food, etc. also produces a nutrient called phosphate. It is considered a nutrient and is beneficial to soil, it is NOT very beneficial to ponds.
Phosphate is a primary reason behind algae growth.
The excess phosphate and nitrogen can quickly cause algal bloom.
Dissolved oxygen is natures primary way to combat nitrogen and phosphate.
There are all types of aeration such as diffused aeration, fountains, waterfalls, windmills, paddle wheels....
Increased dissolved oxygen levels will help the pond bacteria thrive and improve the reduction of ammonia, nitrites and nitrate, which fuel algae growth. (will also help fish digest and convert food to energy)

Add Bacteria:

There are multiple brands of pond bacteria additives that can come in different varieties like liquid, powder, packets and gels.
You can add the bacteria directly to the filter media to establish a strong colony in the filter or simply add the product directly to the pond, which allow the bacteria to colonize all over the pond and begin consuming the available nutrients in the water, starving the algae and breaking down waste.

Color the Water:

Water colorants will tint the water blue (black also available) which inhibits algae growth by reducing sunlight in the water.

Barley Straw:

A common method to control algae is Barley Straw Bales, Balls, Pellets, Flakes.....as the straw decomposes, it releases a natural algal inhibitor. Also available are the products of liquid Barley Straw Extract with the same benefits of barley straw.

UV Clarifier/Sterilizers:

A UV (Ultraviolet) unit should be installed between the pump and the filter to eliminate up-to 99% of the pond's green water.
The UV light kills algae bloom (Planktonic Algae) and disease causing microorganisms.
UV Clairifier/Sterilizer will Not have any effect on hair algae (Filamentous Algae).

Chemicals:

There are numerous chemical products (water treatments) available for algae control.