Problems with pumps and stirring

[BenjA]

Hi:

I using the Chi-Bio (V1.2) for a laboratory evolution and I have some problems that I hope you can help me with:

Stirrer:
– I was using the magnetic stirrer is recommend in website (Fischer 12mm), but it doesn’t stir evenly (setting a rate of 0.5), as the stirrer start hitting the walls of the vial or just spin unevenly, which affect the culture mixture. I change to a bigger stirrer (18 to 20 mm) and I have seen in the last days that the system stop stirring randomly, even if all the rest of the modules are working (temperature, pumps, OD reader). When this happen, I restarted the experiment and sometimes it works back again and sometimes takes a while. What could be wrong?
– The new stirrer has a good mixing, and doesnt seems to hit the wall of the vial as the previous one.

Pump:
– Last weekend one of my pumps stop working and is not responding to the Chi-Bio App. I dont see any problem with the mechanical parts and the rest of the pumps are working correctly. Can maybe be a hardware problem? Sometimes I got the error message that I lost comms with the pumps, but they still works.
– I try to use the dither OD function in the app, but the in-pump is fix at 0.02 and doesn’t change with the experiments, so it can not be diluted to the desired OD.

Hope this is useful to understand the problem, happy to send more info if needed 🙂

Bests!

[harrison]

The stirring system can be quite sensitive if it is a large stirrer with strong magnet, FOr this reason I would strongly suggest the recommended stirrer and running it at higher speed if you need better stirring.

Pump – It could be a hardware issue, have you tried a different pump board on the same reactor? If that works, but the othe rpump doesnt, likely that pump is broken.
For the OD function, the Pump=0.02 is the maximum rate. So, this is what you might expect it to deliver if you are way above the target OD. If you are delivering this amount of pumping but you are still unable to reduce the OD of growing cells, it could be the pump is not making a good seal on the tubing or for other reasons it isn’t ACTUALLY pumping. Look at the troubleshooting guide in the manual as there are various ways to improve this, e.g. putting some tape in the pump head, or putting a one way check valve between the pumps and the reactor so liquid cant flow backward at any time.

Harrison

[Author]

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