stirrer at 0.5 and less speed stopped working

Tagged: Stirrer

This topic has 5 replies, 3 voices, and was last updated 1 week ago by ReynelUrreaC86.

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September 26, 2025 at 7:46 am #1960

Abdurrahman Adam
Participant

Hi,

I noticed that the stirrer was working fine at 0.5 speed, and then it stopped after some time. I opened the cover and didn’t identify any hardware problem. Moreover, the stirrer will work again after I lift the vial up and then place it on the heater plate again. Anyone can suggest how to fix this? Thanks

September 26, 2025 at 8:51 am #1961

harrison
Keymaster

Hello
Are you using the standard recommended stir bar? This behaviour is something we have observed if using a different (often much larger or less smooth) stir bar. Also, it will be more reliable if you run at higher than 0.5 speeds where possible…

September 26, 2025 at 10:00 pm #1962

Abdurrahman Adam
Participant

Hi, thank you for the reply

Yes I am using the standard stirrer from labmaker.

Does placing the washer helpful in this issue? Also what is the recommended stirring speed for overnight culture? Since vortexing happens with 0.8

September 27, 2025 at 9:30 am #1964

Abdurrahman Adam
Participant

Hi Harrison,

I tested to increase the speed up to 1.0 and still it stopped in the middle. Since I dont need the OD600, I will try to change the code to make the stirrer work continously to prevent it stalled during OD measurement.

September 29, 2025 at 8:45 am #1965

harrison
Keymaster

OK, yes indeed you could just tell the device to stick at 0.5 speed and NOT turn off the stirring at any point.
Another thing is to make sure your tubes are going RIGHT to the bottom of the device and touching the heat pad (check with an empty/no water tube) as if they are getting stuck above this it may be they are too far from the rotating magnets…

May 29, 2026 at 8:37 am #1994

ReynelUrreaC86
Participant

Hi there!

We are having some trouble with our stirring in the Chi.bios when using the turbidostat function (target OD at 0.4). We hear the stirrers start (set to 0.5) and see they are indeed stirring when we lift the glass vials out of the reactors, but once the cultures reach the target OD, the stirrers somehow stop or get stuck, and cells precipitate to the bottom. When checking again after a few hours, we see improper mixing and a cell precipitate at the bottom. After manually shaking the glass vials and putting them back in the reactors, the stirrers start again, and we see a significant peak in the OD.

Have you been able to solve this problem?

Thanks in advance for any suggestions!
All the best,
Reynel
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