article: Algae and Nitrogen in your Water Pond
Algae and Nitrogen in your Water Pond
Water ponds are beautiful, but we need to keep the algae from making our ponds
ugly. In the spring, microscopic algae often flourish, giving way for green
water. Green water offends the pride and spoils the enjoyment of many fish
keepers who may have to buy a biological filter to clear up the water.
The largest constitute of algae is chlorophyll, which oxygenates the water in
the presence of light but de-oxygenates it in the dark, sometimes leaving
insufficient oxygen for the filter bacteria before dawn. Some of the filters are
in-suffient in green water.
Experience has shown that a reduced dosage of either the freeze-dried or live
bacteria preparations applied to the filter system every morning when dissolved
oxygen levels are rising can clear a pond in ten to fourteen days. Continually
replacing the bacteria after a few hours of warmth during daylight hours, they
will gradually become established.
Interestingly, green water is usually indicative that the filters are
functioning perfectly. Green water can be very beneficial to koi. This will
enhance the color patterns of small koi and providing essential nutrients to
newly hatched fry. On Japanese koi farms, green water is encouraged in the fry
ponds with the addition of large quantities of manure.
Nitrate poisoning is responsible for more mysterious disease and deaths than any
other disturbance. Symptoms take up to three weeks once the koi have been
exposed. Large Koi may respond to excess nitrate in the water by lying on their
sides and are generally lethargic. They will continue to feed, however small koi
will probably die.
Testing water conditions regularly while new filters are becoming established,
after the winter when mature filters are becoming fully operational once again,
or following some other disruption, will enable you to monitor any dangerous
increase in nitrate levels. Reducing or even withholding food from koi in order
to limit the ammonia production is one way of minimizing potential damage. You
can also add zeolite to the filtration system and this will extract surplus
In cases of high nitrate levels you may need to change as much as thirty to
forty percent of the water daily. If the nitrate level is extremely high, you
can neutralize it to some extent by adding salt to the water. This will
discourage many parasites and bacteria growth. You should not add salt to the
water if you have already added zeolite in the filter. This will release ammonia
back to the water.