ALGAE
Two Types
1. Suspended algae/green water/plankton/pea soup/single cell algae
2. String algae/blanket weed/hair algae/filamentous algae. But, the short velvet type of algae that
covers everything in the pond is beneficial.
Provides natural appearance, uses nutrients from the water, provides
oxygen during the day, fish nibble it.
1. Algae needs nutrition [nitrogen, phosphorus] and sunlight. The nutrition comes from bi-products from
fish waste, dead and decaying leaves, decomposed fish food, and plants. Excess debris on pond bottom can cause
string algae.
2. Temperature and season change:
air temperature warms in spring, beneficial bacteria are just starting
to grow, plants not filled out yet, pond is full of nutrients from dead decaying
leaves and debris so algae thrives.
3. String algae tends to grow in water with high pH values. Also tends to flourish in waterfalls and in
shallow streams because sunlight is more intense there and water provides
constant supply of nutrients.
4. Too many fish/Over feeding fish and excess food providing nutrients for
algae
5. String algae is concentrated around edges of pond because water
temperature is warmer and there is less water circulation.
1. Increase circulation to edges.
Pump at least ˝ the total volume of your pond every hour and have a
filter that will filter the total volume of your pond every 3-4 hours.
2. Manually clean edges with your hand or soft brush.
3. Add barley straw bundles
4. Create shade with 50% to 70% plant coverage over surface of pond. Add plants of all aquatic types to compete
with algae for nutrients.
a. Water lilies’ spreading pads shade the water
b. Underwater plants, like anacharis, [one bunch per one or two square feet
of surface area,] and floating plants like water lettuce and water hyacinth
with free roots absorb nutrients directly from water and help block light
5. Because the algae are fed by ammonia (fish waste), be sure that you have
a properly sized and biological filter working to capacity. Be sure filter is clean.
6. If pond muck on bottom is thicker than one inch, scoop, siphon or vacuum
some out.
7. Introduce beneficial nitrifying bacteria which will starve out the
algae. [E.g., Microbe-Lift.] Bacteria
also breaks down some sludge build-up.
Bacteria need place to grow:
biofilter, rocks, plants, filter media.
Be patient as pond ecology fixes itself as new bacteria grow.
8. Beneficial bacteria’s effectiveness is enhanced by use of an
aerator.
9. Balance the pH: should be
between 6.8 and 7.4. Some experts,
however, say not to be concerned about the pH of your pond.
10. Prevent run-off from rain or other parts of yard, garden or patio into
pond.
11. In Koi pond use rock salt @1pound per 100 gallons as prevention, not
treatment, for string algae. Remove
excess algae before dosing with this level of salt as the decaying vegetation
will pollute the pond and reduce oxygen levels. Don’t do this in a water garden as will harm the plants.
1. Do not clean pond filter with tap water which will kill beneficial
bacteria.
2. Do not change the water or do major water change because will have green
water again in a few weeks
3. Do not use chemical algaecides because they may harm plants and the
algae will return. The dead algae
builds up on the bottom of the pond and creates an organic “compost pile” to
the pond. This provides nutrients and
will cause more algae to bloom in a few weeks.
4. Ultraviolet clarifier will destroy floating algae but not recommended
unless you have zero ammonia. UV will
not help with string algae.
1. Remove dead leaves or spent flowers.
Use skimmer or manually remove.
2. When plants begin to take over, remove some and share with club or
friends, or compost.
3. Leave an inch of organic muck on bottom of pond.
4. Use barley straw bundles as preventative from recurring string
algae. Since it takes 3-8 weeks for
barley straw to become an active organic algaecide, start in early spring.
5. Don’t over feed or keep more fish than your pond will support. One goldfish per 5 square feet and one Koi
per 10 square feet are a good rule for most ponds. Or no more fish than can fit nose to tail across widest diameter
of your pond.
1. In spring remove fish and plants, water from pond. Liberally sprinkle kosher salt [not table
salt]. Let it sit for three days and
then brush off and rinse and clean the pond thoroughly
2. Then add barley straw bundles as preventative from recurring string
algae.
1. Bottom covered with submerged plants
2. Skimmer and large biofilter
3. No/few shallow edges. Good water
circulation.
4. Pond is deep, at least 24”, to reduce sunlight reaching bottom.
J.
Lewis 5/7/02 for the Tucson Watergardeners.
Sources: www.absoluteponds.com ; www.pondmarket.com ; www.pondsolutions.com ; watergarden.com ; www.lagunakoi.com ; www.plantconnection.com ; www.pondguys.com