Velda CROSS-FLOW BIOFILL Mode D'emploi page 11

micro-organisms and by doing so, stimulates the growth of water plants. Use of biological filtration
is recommended when there is stagnant plant growth and/or extreme algae growth. Initially, the
filtration will be exclusively mechanical, but over the course of time, the material becomes
biologically active. The biological working of the filter is stimulated by the inoculation of the filter
material with a special bacterial culture, such as Bacterial Filterstart.
THE CROSS-FLOW BIOFILL
The Cross-Flow Biofill has more advantages compared with other filter systems. The capacity of
the "working content" and also the purifying capabilities of the filter are larger than with current filter
types. The biological function is very effective, because the system is an excellent medium for
growing bacteria through the breakdown of suspended waste. The filter is very easy to connect
and is supplied with filter materials and hose connectors (see also installation). The Cross-Flow
Biofill can be placed in ponds with a maximum volume of 10,000 l water. As an option, a second
filter can be connected. When connecting the outflow openings to each other, the filter installation
can filter ponds up to 20,000 litres of water. The outflow opening should be 50 mm.
INSTALLATION
The filter contains four perforated partitions (1). These are to be placed so that the first partition (by
the intake opening) has the perforation on the top, the second on the bottom, the third on the top,
and so forth. With this assembly, the water stream goes up and down. See illustration. The Cross-
Flow Biofill comes complete with all the necessary filter materials. Carefully rinse the filter materials
before use. Use the enclosed net for the filter coal. Place the lid (4) in the correct position on the
filter, ensuring that the connecting ring is placed in the appropriate groove and close the filter with a
fastening clamp (6). It is recommendable, before closing the cover, to fill the filter with water. The
filter is constructed and meant for use only for the filtration of pond water. If you want to use the filter
in the winter period, the installation of a Velda Pond Heater is recommended.
Connecting the pump
The filter has a 20/25/38 mm and 32/40 mm hose connector for the intake opening (7). To prevent
capacity loss, the hose connector must be sawed off to the diameter of the pump hose. A flexible
reinforced pump hose is recommended. Attach the hose with a fastening clamp. Velda recom-
mends using a minimal 2500 and maximal 5000 litres per hour pump capacity. The recommended
pump is Green Line 5000. The outflow opening of the filter is 50 mm (8). Use a suitable flexible
hose here and secure this with a hose clamp. To prevent leakage problems, the outflow opening
should not be made smaller.
MAINTENANCE
If the water output of the filter decreases considerably or if the lid is leaking, the filter material must
be rinsed out. It is generally enough to rinse it out several times with tap water. The fastening clips
have been constructed in such a way that they will spring open when the pressure in the filter will
become too high. This will occur for example, if the filter material should contain too much dirt or if
any filter material would be used with a too small porosity for water. It is recommended to replace
the active coal once or twice a year, or at least, at the start of the new pond season.
If the water supply to the filter is stopped for four or more hours, the filter material must first be
rinsed before filtration resumes. This prevents the micro-organisms which die from an oxygen
shortage from getting in the pond. It is recommended to use Bacterial Filterstart.
OPTION: UV-C UNIT
Velda offers special 9 Watt and 18 Watt (included as standard) UV-C Units for this filter. The unit
can easily be placed in the holder (2). Replace the cap (5). The benefits of UV-C are universally