Venturis work on the principal of increasing the flow rate of
water, which causes a corresponding drop in pressure, which
causes suction, and this is used to inject air into the water.
Hundreds and thousand of micro bubbles are released into
the water thus raising the oxygen level in your pond.

Water without oxygen cannot support fish or other aquatic life.
For optimum fish keeping conditions and in order for fish to
thrive there should be an oxygen concentrate of at least 8 mg/l
in your koi pond. The exchange at the water’s surface of
carbon dioxide to oxygen is not sufficient, thus the use of an
Ultra Zap Venturi on the return line to the pond will result in
better aeration and the water quality will be greatly improved.

In the hot summer months it is vital that your fish get enough oxygen, because this is when they need it most. Through good pond management and the use of an Ultra Zap Venturi, the DO concentration can be very easily maintained at a level ideal for your pond.