WHAT IS ALGAE?
Algae is a
living aquatic organism that multiplies rapidly in warm temperatures. Algae
contains chlorophyll and grows through the process of photosynthesis. Algae
spores are constantly entering pools, brought in by wind, rain or even
contaminated swimsuits or equipment. When conditions such as unbalanced water,
warm temperatures, sunlight, or the presence of nitrates exists, an algae bloom
can occur seemingly overnight. Algae growth is facilitated by poor circulation,
filtration and sanitation.
WHAT PROBLEMS ARE CAUSED BY ALGAE ?
The first noticeable problem is the dirty appearance of
pool water. The second problem is that it requires a great deal of effort to
completely rid the water of algae. Algae itself is not harmful to swimmers, but
pools with algae may also harbor pathogens like E-coli bacteria. Algae also
clogs the filter, decreasing its effectiveness and ability to remove
contaminants. Algae also creates an increased chlorine demand, so more chlorine
needs to be fed into the pool.
WHAT TYPES OF ALGAE ARE
THERE?
There are over 21,000 known varieties of algae! The most
common found on pools include:
GREEN
ALGAE:
An extremely common variety, green algae will
usually appear immediately following a hazy water condition caused by poor
filtration and/or sanitation. It is frequently found free floating in the
water, although it also will cling to the walls. It reduces water clarity,
appears as "spots" on pool surfaces, or as "sheets" where large wall sections,
or even the entire pool, is coated in a green slime.
YELLOW ALGAE:
A wall clinging variety, also called mustard
algae, is usually found on the shady side of the pool. It forms sheets on
surfaces and can be extremely difficult to eradicate completely. This variety
is resistant to normal chlorine levels and must be dealt with agressively.
Yellow algae can bloom in the presense of normal sanitizing levels and proper
filtration.
BLACK
ALGAE:
Perhaps the most aggravating strain of algae,
Black Algae is extremely difficulty to eradicate due to its strong roots and
protective layers over the top of the black algae plant. Black algae will
appear as dark black or blue/green spots, usually the size of a pencil eraser
tip. Their roots extend into the plaster or tile grout, and unless the roots
are destroyed completely, a new head will grow back in the same place. The
heads also contain protective layers to keep cell destroying chemicals from
entering the organism. Like yellow algae, black strains can bloom even in the
presence of normal sanitizing levels and proper filtration.
PINK
ALGAE:
Not really an algae at all, but a form of
bacteria. Appears as spots or streaks in corners and crevices. It is slow to
spread and rarely blooms over the entire pool.
HOW IS ALGAE
PREVENTED?
Proper water balance and
sanitizer levels will prevent the opportunity for algae to bloom. General
cleanliness of the pool is also important, since organic material and bacteria
can contribute to algae growth. High pH and low chlorine (or other sanitizer)
can give algae a opportunity to bloom. Regular brushing of seemingly clean
pools prevents dirt from building up in the pores and crevases of the plaster,
where Algae colonies can get a start.
Chemicals:
The use of algaecides (Algae killers) and
algaestats (Algae preventers) provides a back up to normal sanitation and
filtration, and for many pools in some locations is a necessary routine . Such
chemicals include:
POTASSIUM
TETRABORATE: This chemical, when added to the pool water in proper
dosage, prevents algae from converting carbon dioxide into the fuel it needs
for growth.
CHITIN:
Chitin acts as an
algaestatic due to its ability to coagulate and remove a wide variety of
suspended materials and impurities from pool water. This allows the sanitizer
to more effectively kill contaminants. It also improves the effectiveness of
the filtration equipment.
ALGAECIDES AND ALGAESTATS:
1. QUATERNARY AMMONIUM COMPOUNDS: Also called Quats, this is a low grade
algaecide.
2. POLYMERS: Polymers are long, complicated
chemical chains that behave in water both as an algaestat and an algaecide.
They are available in percentage strength of 30-60%, are non foaming,
and work well as general, all
around algae treatments. Poly-Quats are a blended
compound of polymers and quats.
3.
COPPER BASED: Copper is a proven algaecide and algaestat.
Available in varying non foaming strength of 3-10% copper works well on all
types of algae. Copper has the drawback of staining white plaster surfaces a
light blue/green color if it precipitates out of solution. Most copper based
algaecides are chelated, which means that agents have been added to prevent
this.
4.
SILVER BASED: Silver has been shown to be an
effective bacteriostat, which means that it works to prevent bacteria from
reproducing. It is non foaming and effective with pink algae. In high doses,
reactions with sunlight can cause colloidal silver to deposit as black stains
on white plaster. When using copper or silver algaecides, the use of a
sequestering agent is recommended.
CHLORINE ENHANCERS:
These are
not algaecides, but provide a synergistic boost to hypochlorites. Sold under
trade names like Mustard Buster, Yellow-Out or Yellow Treat, they are most
effective on yellow algae.
TOO LATE TO PREVENT IT...HOW DO I KILL
ALGAE?
First of all, balance the
pool water, paying particular attention to pH. Secondly, check the filter
system and backwash and clean if necessary. Ensure optimum circulation and run
continually until the pool clears. Backwash as
necessary.
For suspended green algae, shock/superchlorinate the pool. Brush
the walls and floors, vacuum, and filter continuously. Backwash the filter as
necessary.
Following superchlorination, allow the chlorine level to fall 5
ppm and add an algaecide. Brush the pool again. When it all settles, vacuum the
pool to waste. Check the water chemistry and rebalance if
necessary.
For algae which is not suspended, but only clinging to the
walls, follow the same advice above, first shock, brush, then add an algaecide,
brush again, vacuum to waste and backwash the filter. Use of a steel bristled
brush is recommended for algae on plaster pools. Use nylon brushes on
vinyl.
For black algae, the brushing part is very important. The
plant's protective layers must be destroyed so the chemicals can destroy the
plant from the inside out. Pumice stones work well to knock off the heads of
black algae. Also try sprinkling granular trichlor over the spots (of course if
they're on the wall this is next to impossible). Rubbing the spots on the walls
with a trichlor tablet or stick may be effective in knocking off the heads and
getting trichlor directly to the roots. Follow up with a dose of copper
algaecide or high strength polymers.
If the algae is resistant to all of these measures, or has been
a persistent ongoing problem, the pool may have to be drained. Acid wash and/or
pressure wash plaster and marble dust surfaces to remove the algae roots
imbedded in the plaster. Then change the sand in a sand filter, or the
cartridge if the filter is a cartridge type. For a DE filter, remove the
elements, spray clean, soak in a 10:1 water/bleach solution, rinse and replace
the D.E. powder. |