Calibrate the pumps and set the level

The pump channels and the 12 V supply were checked in Nutrient solution.

1. Fill the media bottle with water.
2. Calibrate the pumps on the Protocols page, waste on PWMOne of the HAT's five switched power outputs. In this build: 1 stirring, 2 media pump, 3 waste (product) pump, 4 CO₂ solenoid (relay), 5 heating. 2 and media on PWM 3: catch each dispense in a tared weighing boat on the analytical balance and enter what it weighed (1 g of water is about 1 ml).
3. Unscrew the cap, empty, rinse and dry the vial, and fill it to 14 ml with water.
4. Screw the cap back on, and weigh the vial to confirm the volume.
5. Adjust the Media Out tube so it is only just submerged at that level.
6. Run the media and waste pumps, then weigh the vial again.
7. Repeat from item 5 until the vial holds 14 ml after running the pumps.

Why the Media Out tube sets the level

The waste pump over-runs each dilution by design, so the height of the Media Out tube is the level setpoint, not the ratio of media to waste volume. See forum #801.

Parts

• 2×12 V peristaltic pumpsearlier step
• 2×250 ml GL45 borosilicate bottleearlier step
• 1×Pioreactor 20 ml glass vialearlier step
• 1×O-ring vial capearlier step

Tools

• 1×Analytical balancetool

Check your work

1. Which pumps have you calibrated?

   • The waste pump and the media pump
   • The waste pump, not the media pump
   • The media pump, not the waste pump
   Show the answer

   Answer: The waste pump and the media pump

   • If you see The waste pump, not the media pump: Calibrate the media pump (PWMOne of the HAT's five switched power outputs. In this build: 1 stirring, 2 media pump, 3 waste (product) pump, 4 CO₂ solenoid (relay), 5 heating. 3) too.
   • If you see The media pump, not the waste pump: Calibrate the waste pump (PWM 2) too.

2. After running both pumps, what does the vial hold by weight?

   • More than 14 ml: it has filled
   • 14 ml, the same as before the run
   • Less than 14 ml: it has drained
   Show the answer

   Answer: 14 ml, the same as before the run

   • If you see More than 14 ml: it has filled: Push the Media Out tube a little lower: it sets the level, and should be only just submerged at 14 ml.
   • If you see Less than 14 ml: it has drained: Pull the Media Out tube up a little: it sets the level, and should be only just submerged at 14 ml.

≈ 0.02 g CO₂e per view