[Shalni]

Resolved! haha
I did not realize everytime you stop the experiment (to change media etc) the OD regulator switches off and doesn’t switch back on when you start again.
Even though my exponential growth happened a few hours after the switch the od setpoint went to zero exactly when I restarted the experiment, I just didn’t see the effects till some time later.
No mystery turn off!
Sorry for the trouble
Potential recommendation to keep the switch on unless the user resets the experiment but other than that it was a human issue.

[Shalni]

-Sadly I stopped the experiment before manually changing the pumps and I don’t remember if the switch was still blue before. I’m not sure if the switch state has a log record anywhere I can check. The od set point did change to 0 in the data files.
I will remember to check the switch if it happens again.

-Oh I see thanks for clarifying. I was just referencing your above comment “have you made sure that the liquid level in the reactor is always significantly below that in the fresh media and waste media containers” but not any part of the manual!

Thanks, Shalni

• This reply was modified 2 years, 7 months ago by Shalni.

[Shalni]

Hi Harrison,

Thanks for the advice.
I pushed down the tubing on the output pump and double checked the seal.
I reran my experiment and this time got no errors however about 10 hours in the OD regulation stopped working.
It held at my target of 0.4 for quite awhile but then both the input and output pump stopped and the OD saturated.
When I came back this morning I manually diluted the culture by running the pumps and the OD regulation started working again.
Any ideas?
This link has the output plots for OD, and pump rates from my experiment.
https://drive.google.com/drive/folders/1fpZo-hMuZzVzpBVAuyRMYalJvrMojHnO?usp=sharing

Also to clarify, the top height of liquid for my fresh media and waste should be a lot above the top height of liquid in my reactor? Do you mind explaining why this is the case? (especially for the waste side) Does the actual tube end need to be at a specific height as well?
I have attached an image of my current setup in the link above as well. Right now my media and pump/reactor is on a lab bench with a large amount of fresh media and some waste media to start. The tubing rests at the bottom of each container.

Thank you so much for your help
Shalni

[Shalni]

Hello,

I just tried my first unattended run and had a similar problem occur.
About 3 hours into an experiment the OD spiked from 0.3 where it was being maintained to 0.8. This triggered the input pump to spike and caused the tube to overflow and wet the reactor. I’m assuming the overflow is what stopped the run via moisture sensors etc but I was wondering how to prevent the OD spike from occurring again. Ideally I would need things to run smoothly for 4-5 days in Turbidostat mode.

Thanks for the help!

Shalni

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