Decoupling working volume and minimum volume in turbidostat

Software
1

I’m working in the lab with Stijn and Malthe setting up an ALE experiment using the turbidostat. I would like the dosing automation to remove the desired volume (~90%) before adding media back in. Currently it seems there is no way to do this, that instead I can only cycle a certain volume, and that the waste tube must be at the top of the working volume. I don’t want to do this as I would expect that removing only media from the top not to be a representative dilution and I want to remove a consistent percent of the biomass at each cycle.

Has anyone run into a similar problem and if so how have you solved it?

2

Hi :wave:

Hm, I’m a little bit confused about the ask. Can I ask some questions?

  1. Are you using the built in turbidostat, or a custom automation? If the latter, can you provide the code or high level protocol?
  2. Where do you expect the waste tube to be positioned in your experiment, vs where does the software expect it to be?
3

I’m using the built in automation, and I want to position the waste tube at the 3mL level but have a working volume of 20mL, two things which I can’t seem to decouple in the experiment. In other words, I’d like to have a volume of 20mL most of the time, but be able to draw it down to 3mL before adding more media.

4

Hmm, so like:

usually: 20ml, and when you “exchange” media: you reduce to 3ml, then fill back up to 20ml?

5

exactly

6

Upon review, I think I once again want to make a design change here. Perhaps “max working volume” is doing too many things: position of efflux tube, and (suggesting) the working volume. Your pattern breaks that, and makes me rethink this. Let me get back to you shortly.

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