"Paul M." wrote:

I have constructed a pond that does not recirculate water, but
intercepts well water from a campus cooling system and runs it through
the pond prior to flowing into the storm sewer. The water is cool
and clear, but tends to warm up while it moves through the pond. Temp
can be regulated by the rate of well water flow through the pond.

Alas it grows algae. I have experience with a a similar sculpture
pool with the same water set up that we periodically shock the pool
with swimming pool chemicals and periodic scrubbing to keep clean.

The intent of the new pond is more 'naturalistic' and I would like to
keep water plants etc. which wouldn't like being chemically
shocked!!! I thought perhaps some fish could keep the algae in some
sort of equillibrium. The water does not turn green because of the
constant water turnover, but algae grows from the bottom. Does
anyone see hope for fish??? to be seasonally kept in such a set up to
control algae, or other suggestions?

I have virtually the same thing. Mine is an old mortar and stone
18,000 gallon (17'x 47'x 2-4') swimming pool that is spring fed. We
filled in the deep end so that it is 4' at the deepest. The pond fills
in about 24 hours from the springs. The overflow goes into the storm
drain which goes into a creek. The spring water's temperature is 50 F.
The pond's temperature gets up to 70 F by the middle of summer. When
first filled with water, it quickly covered over with string algae. I
put 12 trap-door snails in the pond and they multiplied at a fantastic
rate. Soon they were eating the string algae. Frogs came into the pool
at an alarming rate. Marginal plants are doing very well. The water is
reasonably clear. Algae is caused by nutrients in the water and
sunlight. Here is what I do:

€ Planted 10 water lilies and one lotus, which have large leaves that
shade the pond surface. Shade is important in preventing algae. I let
Azolla caroliniana ("Fairy Moss") cover the surface during the winter
and early spring to provide shade before the lilies and lotus form their
leaves. Then I scoop most of the Azolla out with a swimming pool
skimmer net in mid-spring so I can see the fish. It doesn't come back
until the next winter.

€ Planted about 64 marginal filter plants in baskets with clay soil
(Walmart's cheapest Kitty Litter) and no fertilizer around the edge on 8
- 2 foot x 8 foot black plastic greenhouse benches about 5 inches below
the water surface. Marginal plants remove nutrients from the water and
prevent algae. Fish like lurking under the benches and frogs like
sitting on the plants.

€ Introduced trap-door snails into the pond which eat dead material in
the pond and hence break down plant nutrients. The snails multiply
nicely each spring and take care of dead plant material.

€ Sunk oxygenator plants on the bottom, Anacharis and Hornwort. I also
have a 1.7 CFM, 40-Watt air pump and two aerator heads to keep the
oxygen levels up in the winter when the plants become dormant. The
higher oxygen level helps support fish and aerobic bacteria. Adding the
aeration changed the water from a tea color to a more clear color.

€ Floated a bale of barley straw under the spring pipe and over an
aerator head. This helps prevent algae when it tries to bloom in the
spring before the marginal plants get going.

€ Introduced 100 native golden shiner minnows. They eat mosquito larva
and help keep the plants in check and don't seem to add to the nutrient
load too much. They are doing very well and have multiplied. You can
see the different sizes of minnows from broods from different years.

€ Applied one dose of algaecide (AlgaeFix) in early April if necessary
to get a start in clearing the spring algae growth.

€ Added bacteria (Microbe-Lift Spring/Summer) in early April to help
eliminate the dead algae and other organic matter.

€ Fertilized water lilies in early May with Once-A-Year Aquatic-Spikes
from AgSafe (a div. of AgriTab Corp., Clearfield UT). They contain:
Ureaform, Amoniam Phosphate, Potassium Nitrate, Potassium Sulfate,
Calcium Sulfate, Ferrous Sulfate, Iron Sucrate, Magnesium Sucrate,
Magnesium Sulfate, Manganese Sucrate, Manganese Sulfate, Zinc Sucrate,
and Zinc Sulfate in a time release format. The are safe for fish and
other aquatic life. The nitrogen in their formulation is 70% ammonium
based and 30% nitrate based.

No filter, no UV, no water pump, no Koi, no problem.

I am in zone 6 and get a lot of hot weather in the summer and cold
weather in the winter.

For a view of our lily pond visit:
http://home.dejazzd.com/shenning/pool8-18.jpg

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