Bottled bacteria is fed into the filter medium at a consistent water temperature of 50 F (usually April 1st). This is done every spring, bacteria is dormant at 39-50 F at 38 F or less it is dead. You are kick starting your system by doing this.

Minimum filter size = 1/3 the size of the surface area of your pond. Example: pond is 30 square feet of surface area, filter bed should be a minimum of 10 square feet (the bigger the better). Or: pond volume in gallons. W x L x D x 7.5 / 60 minutes. Ideal rate of filtration = 1/2 gallon of water per minute per square foot of filter bed. Example: 10 x 8 x 2 x 7.5 = 1200 gallons / 60 = 20 square feet of filter bed (minimum). By using filter matting you get square footage on the front and back of the matting.

The following is a Diagram of the Biological - Upflow Gravity Filter:

This design could also be used in a square or rectangle box.

Basic Requirements are:

• All filters need a bottom drain.
• Water goes into the top.
• All filters need a void space.
• Return pipe must be above pond level.