GENERAL Sizing CONSIDERATIONS from Oase®
In order to reduce the chance of algae growth it is essential to keep water circulating throughout the lake.
In an ideal situation, the lake is of perfectly circular shape with the fountain located in the middle. The water spray is forceful enough to push aerated water to the sides so that no stagnant spots remain.
In the real world, however, lakes are neither round nor is the placement of the fountain in the middle always the most aesthetically pleasing solution. Therefore the following factors should be considered when choosing the number and size of floating fountains or aerators:
Size and Shape of the Lake
A good guideline is to circulate one acre foot or 325,851 gallons of water once every 24 – 48 hours, depending on the climate. Also it is important to keep as much water as possible in circulation – from the fountain all the way to the sides of the lake. This means a long or irregularly-shaped lake may be better served by two or more fountains or aerators, regardless of the overall volume of the lake.
Nozzle Spray Pattern
Spray patterns determine the effectiveness of aeration by how well the water is moved away from the fountain to the sides of the lake (circulation) and by how fine the droplets are sprayed into the air (oxygen enrichment). Spraying water into the air is the most effective way to enrich it with oxygen as the volume of air relative to the volume of water is very large. Sub-surface aeration is less effective and does not circulate water throughout the lake as well.
Warm climates with a lot of sunshine require higher performance from an aerating fountain or floating aerator. Sunshine and heat contribute to algae growth and even borderline stagnant spots may become overgrown relatively quickly. In order to effectively circulate more water, a larger unit or multiple units may be needed.
Prior Algae Problem
An existing algae infestation is often best approached by manually or chemically cleaning the pond and then running the fountain continuously in order to keep the growth under control.
Putting It All Together
OASE aerators and floating fountains are available in a wide range of horsepower so they can best match the particular environment in which the unit is going to be used. OASE nozzles are interchangeable and provide the ability to adapt the units to aeration needs or aesthetic preference.
DETERMINING AERATION NEEDS
An easy way to determine surface area – especially of irregularly-shaped lakes – is to outline the lake on a grid with 100 sq. ft units (10 ft. x 10 ft.)
In the example below the lake occupies about 86 of the 144 grid squares. Therefore the lake surface area is 86 x 100 sq. ft. =10,100 sq. ft. This is equivalent to about 1/4 acre (see formula below).
The combinations of pumps and nozzles on OASE aerators and floating fountains allow for the general rule, that – in normal water conditions – 1 1/2 horsepower motors are recommended per surface acre.
A lake of 3 acres could therefore be aerated by three 1 1/2 horsepower units or one 5 horsepower unit (depending on the shape of the lake and aesthetic preference).
To get the volume of the lake, multiply the surface area by the average depth. This number can then be used to calculate necessary flow rates in order to ensure adequate circulation over a given period.
Surface Area (acres) = Surface Area (sq. ft.) / 43,560 sq. ft. per acre Total HP needed= Surface Area (acres) x 1 1/2 HP per acre
Lake Volume (gal) = Surface Area (acres) x Avg. Depth (ft.) x 325,851 gal. per acre foot
lake may require one fountain of given
performance. The spray pattern moves water
to the sides of the lake in
order to ensure proper circulation.A lake of larger size may require two
units to get effectively aerated, with
each unit covering about half the lake. Alternatively, a larger unit could
be used to cover the entire lake.
irregularly-shaped lake may require multiple units in order
to circulate water in the
“knee” and in the far reaches.