The two most common forms
of algae that ponds experience are planktonic algae and filamentous algae.
Planktonic algae is the type that gives pond that distinctive pea green,
soupy color. Planktonic algae in moderation is very important as is the
base of the food chain in a pond. However, it is when it is in excess
that you get the green water.
Filamentous algae is what
you typically see growing on rocks and floating on the surface in mats.
It is the stringy, hairlike algae that you often see in the spring and
summer months. It has little redeeming value.
Algae in moderation is
good for a pond, but when it becomes over abundant, it can cause severe
water quality problems. Algae consumes oxygen at night to continue its
life cycle, so when there is a severe outbreak, large amounts of oxygen
are consumed and can seriously deplete the dissolved oxygen level in a
pond to a point that cause fish kills. Not to mention that fact this its
flat out unsightly.
Algae blooms are caused
by three factors: excess nutrients, too much sunlight and low oxygen
levels.
Nutrients come from a
variety of sources, most notable fish and animal waste, fish food and
dead/decaying vegetation. Other sources would include fertilizer run-off
and run-off from nearby farms and pastures. All of these sources provide
much needed nitrogen and phosphorus that algae need to bloom and grow.
Ponds that sit in direct
sunlight or have very few aquatic plants are also at risk of suffering
from algae problems. This is why generally the most and worst algae
problems occur in the summer when the days are longest.
Finally, ponds that
experience poor oxygen levels will also suffer from algae control issues.
When there are high levels of waste in ponds that are stagnant and still,
oxygen levels can be depleted due to the amount of oxygen needed to break
down the waste. Algae blooms come and go, but when there is little
dissolved oxygen in the water, dying algae will feed new cycles of living
algae because there is not enough oxygen to break down the dead vegetation
before it can fuel more growth.
First of all, algae
should not be looked upon as a problem. It is merely a symptom and a sign
that there are other problems and that your pond is out of balance. What
it means is that one or more of the causes above are the true problems.
A short term, quick fix
is to use an algaecide. However this is just a short term solution
because when you simply kill the algae and leave it to degrade on its own,
it will just fuel re-growth. A quick kill can also cause an oxygen
depletion, which can stress or even kill fish.
The ideal approach for
using an algaecide for quick algae control would be to use the algaecide
as a pre-cursor to the long-term approach discussed below.
A more sound and lasting
approach would be to control the causes of the algae growth – nutrients,
sunlight and oxygen.
Nutrient control involves
limiting the amount of nutrients that enter that water that can feed
algae. This can range from manually skimming debris and waste from the
pond, physically removing the algae, installing an effective filtration
system or limiting the number of aquatic inhabitants, but it should always
involve the use of beneficial pond bacteria. Pond bacteria is crucial in
breaking down and degrading all types of organic waste and should be used
regularly.
Reducing sunlight
penetration is a more difficult because you only have so much control over
that, but a good pond dye and even the addition of aquatic plants can help
to shade the water and limit the sun’s effect. A good rule of thumb would
be 60%-70% coverage with plants.
Improving the oxygen
levels in a pond can be done with a pond aerator or even a pond fountain.
The infusion of oxygen will invigorate pond bacteria, making them more
efficient at their job, while also keeping the pond water circulating
(another deterrent to algae growth).
Effective algae control
begins with knowledge and understanding of the type of algae you have and
what causes the algae to grow. Once you have armed yourself with the
proper information, treating the causes and controlling the sources become
more manageable. Then, year after year, preventative maintenance becomes
second nature and severe algae blooms become less and less of a concern.
For more details, visit
this other
Algae Control article.
Written by Casey Coke, a Marketing Manager
for Natural Environmental Systems, LLC, a global supplier of microbial
solutions for pond and lake management. The company markets their own
brand of
pond supplies under the registered brand name of Pond Keeper.
