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Room 160: General Holding Room

General holding as the name implies holds a variety of species in insulated 1.8 m diameter fiberglass tanks. Each tank has an approximate holding volume of 2 m3. There are currently 25 of these tanks, twelve 0.6 m diameter tanks and one Heath rack for incubating salmonid eggs.

Room: The walls are epoxy coated concrete block and the floor is a specially hardened concrete to prevent water penetration. There are grate covered trenches located between the tanks. The drain lines for the tanks are located within these trenches, as is a drain to the sanitary sewer.

Air temperature in this room is monitored, but is not under the Argus™ system’s control.

Tanks: The 1.8 m tanks are equipped with dual internal stand pipes. The outer standpipe sits higher than the water level in the tank. Holes have been drilled through the bottom of this pipe to effect a self cleaning action for the bottom of the tank. Water is drawn through these holes and up over the inner standpipe. The inner pipe must still be briefly removed either every day or every few days depending upon internal load of fish, to clear waste build-up.

The 0.6 m tanks have a cone shaped bottom, a perforated PVC screen is placed over this cone to prevent small fish from going down the drain. The tanks are designed to self clean. Waste drops through the PVC and is drawn down into the drain line. The cone shape acts to keep waste from settling in the tank. These tanks are also equipped with an external standpipe. The inner standpipe for these tanks must also be removed briefly either every day or every few days depending upon internal load of fish, to clear waste build-up.

Biofiltration: This room is provided with biofilters. The biofilters are located between the inflow lines and the 1.8m tanks. They are made of green ribbed PVC pipe with a perforated PVC screen on the bottom. Number ½ and 2 plastic Tri-packs™ fill the pipe. New biofilters need time to grow bacterial cultures. Nitrosomonas sp. grows first, converting ammonia to nitrite. There is a lag time before Nitrobacter sp. starts to grow. It is during the time that Nitrobacter sp. is becoming established that elevated levels of nitrite could become dangerous to fish. Nitrobacter sp. converts nitrite to nitrate a much less toxic form of organic nitrogen.

Biofilters should not be allowed to dry out. This is particularly important in marine systems; dry-out will result in sterilization of the biofilter.

Biofiltration room
Aeration: Low pressure air for tank aeration is supplied through black ABS pipe that circles the room. Air is supplied from three 1 hp Gast regenerative air blowers located in room 174. Each tank is supplied with two 12" x 1.5" x 1.5" air stones.

Power: This room has only two 115 V and two 220 V electrical circuits. They are located around the perimeter of the room. Each circuit has a duplex ground fault receptacle. If power is lost to a receptacle, check the buttons located in the middle of the ground fault receptacles. If one is sticking out, press it back in to reset the power. If power is lost again, report it to Aqualab personnel. A circuit breaker panel is located on the wall in the main hallway. Please do not open this panel without proper authorization.

Lights: Lighting in this room is provided by weatherproof incandescent fixtures. This room has a fully programmable photoperiod (i.e., the photoperiod can be programmed to emulate that found at any latitude in the world or any artificial photoperiod that the researcher requires). At “dawn” the incandescent bulbs slowly ramp up in intensity, and at “dusk” they slowly dim. The time required to ramp to full intensity and the final intensity of the lights is programmable. The Photoperiod Alarm is set to activate if the lights do not turn on or off as the program requires. The lights can be turned on manually from two timed switches located on the wall near the door to the room. An alarm situation will occur if the lights are left on too long. The current photoperiod for this room is 12 hours ( lights on at 7:00 AM and off at 7:00 PM)

Filtration and Temperature Control located in Room 174

Water Temperature Control: Water temperature is controlled and monitored by the Argus™ system and consists of one plate heat exchanger supplied with cold glycol. Water temperature is monitored going in and out of the exchanger by thermistors located in the pipes. These thermistors are set to activate an alarm (Water Temperature Deviation Alarm) if the water temperature deviates from the target temperature by a preset margin.

The computer control system regulates the position of an actuated modulating valve to modify the amount of glycol supplied to the heat exchanger. This acts to maintain the target water temperature. The water temperature in this room is held at 10°C.

Water Replacement: Water is added to the room’s recirculation system on a regular basis. The volume added is controlled by the Argus™ system which in turn controls the make-up water solenoid valve. The make-up water system is composed of a paddlewheel flow sensor and a solenoid valve on a 1" PVC supply line . Water is fed directly from Aqualab’s pre-filtration system into the room’s sump pit. 75,000 L of water are added in pulses of one minute duration 540 times a day. The number of pulses per day is determined by the volume of water that passes the paddlewheel flow sensor in one minute.

water recirculation filters

Water Recirculation: Water is recirculated around the room from the sump pit to the tanks and back again. Two 3 hp pumps, are used to pump water through two sand filters, a charcoal filter, two four bulb UV sterilizers, and the plate heat exchanger. After the water is filtered and the temperature is modified, it travels to the tanks in room 160. Water overflows stand pipes located either within the tank or beside it and returns via drain lines to the sump pit. The drain lines are found in the trench. Each 1.8 m tank or each set of four 0.6 m tanks has a set of blade valves to direct flow either into the trench (for cleaning and disinfection) or back to the sump (for recirculation).

Recirculation water flow is monitored by a paddle wheel flow sensor which is set to activate an alarm when flow drops below a preset level (Low Flow Alarm). The preset level is dependent upon the minimum required water flow.

System Water Volume: The water level in the sump pit is monitored by an ultrasonic level sensor. When the water level drops below a preset point the make-up water solenoid valve opens. Water is added until the sump is once again full. If the water level drops below 90 cm in depth an alarm is activated (Low Water Level Alarm) and the make-up water solenoid opens. If the water level drops past 60 cm, the pumps will be turned off by the control system, to protect them from burnout. This will activate another alarm (Low Flow Alarm). When the water level rises above 60 cm the control system will reactivate the pumps, thereby restoring flow. When the water level rises above 90 cm the Low Water Level Alarm will be deactivated, and when the water rises to 130 cm the make-up water solenoid will go back into water replacement mode.