Functional as a chemostat?

[Ashley Alexander]

Has anyone ever attempted to use this Turbidostat as a chemostat by overriding the dilution rate calculation programming and just manually setting a dilution rate? We have used chemostats for many years in our lab and they require at least 350ml per vessel so this smaller more affordable model is appealing especially if it could function as both a chemostat or a turbidostat. 

Thanks!

[Chris Takahashi]

The issue with this turbidostat is that it's made to work with poor quality pumps.  The feeback loop in the turbidostat compensates, but if you ran it open loop (as a chemostat) the rates would drift some.  People rarely talk about how much change in dilution rate over time is acceptable in cheomstats (many groups just assume their pumps are perfect).

I think the bottom line is that you need to do some testing and decide if it's good enough.  In the software you can just set the OD to something big like 100 and set the minimum dilution rate to whatever you desire to get chemostat behavior. 

Chris

[Andrew Morgenthaler]

But when you set the OD to something very high, won't the pump never actually add any medium because it won't ever get to that OD? So in this example of setting the OD to 100 the dilution rate would be zero?

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[Chris Takahashi]

The computed dilution rate would be zero, but there's a parameter for the minimum.  The dilution rate is max(computed rate, minimum rate).

On Tuesday, October 3, 2017 at 3:18:04 PM UTC-7, Andrew Morgenthaler wrote:

But when you set the OD to something very high, won't the pump never actually add any medium because it won't ever get to that OD? So in this example of setting the OD to 100 the dilution rate would be zero?

On Tue, Oct 3, 2017 at 4:10 PM, Chris Takahashi 

 wrote: