Vedlegg 6: Regarding measurement of water parameters and oxygen backup
Oxygen Dissolving System and Oxygenation Backup
Aqua Maof RAS uses a special oxygen dissolving system that is part of our patented RAS design. This
system uses the natural weight of a water column to create dissolving pressure, therefore not
requiring special high pressure water pumps for the use of oxygen cones. All recirculated water flow
passes through an ODS just prior to entering each fish tank. The oxygen gas flowing into the ODS is
adjusted according to the demand by fish in each tank. Each tank has at least one ODS and grow-out
tanks usually have multiple ODS to supply sufficient oxygen and have good system duplication (large
tanks have significant value of fish).
The ODS is designed with an overflow pipe that will allow water entering the ODS to enter the fish
tank should there be a flow greater than design capacity of the ODS or if the ODS would plug or flow
be reduced because of some problem and an outlet pipe that gravity flows into the fish tank below
water level. This inlet is below water level to avoid degassing dissolved oxygen in a turbulent entry
above the normal water level. At times when all electricity is off and water circulation pumps stop
this ODS will automatically reverse water flow and use the normal outlet as an inlet to the ODS and
the oxygen gas creates an airlift lifting water out the overflow pipe into the fish tank. This
supplements the in oxygenation in the tank provided by emergency oxygen diffusers. The oxygen gas
flow can be increased if additional CO2 gas stripping is temporarily required when all water
recirculation has stopped. Typically to save oxygen during emergency use of oxygen diffusers in the
bottom of fish tanks designers use high efficient ceramic type diffusers, at greater water depths for
commercial production of market sized salmon these diffusers can be sufficiently efficient to allow
CO2 to increase to harmful concentrations should there be longer periods of electric power outage.
This is the scenario where the reverse flow of the Aqua Maof ODS becomes very important.
Water Chemistry Parameters Measured in Production Tanks
The photo below shows the oxygen flow meters and the example for output of dissolved oxygen,
temperature and pH monitoring. The ODS that is supplied from this oxygen panel is on the right.
Additional measurements are made for alkalinity, total ammonia nitrogen, and carbon dioxide.
There are two oxygen flow meters on this panel; the flow meter on the left controls the quantity of
oxygen gas flowing into the ODS, and the flow meter on the right controls the quantity of oxygen gas
delivered to the oxygen diffusers in the base of this fish production tank. There are four valves plus a
solenoid valve for automatic control of the emergency oxygen diffusers. The four manual valves are
used for selection of use for the main oxygen pipe line or the emergency pipe line and the by-pass
valve to allow flow from either supply pipe to the ODS or emergency diffusers.