> For the complete documentation index, see [llms.txt](https://help.sbtinstruments.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.sbtinstruments.com/more/how-to-guides/hit-the-right-concentration.md). # Hit the right concentration Pick the dilution that lands your culture inside the BactoBox® working range. Your BactoBox® measures accurately when the vial holds 30 000 to 5 000 000 bacteria-sized objects per mL, cells and particles from your medium alike. Most cultures are far denser than that, so you dilute them first. When you follow a culture through its growth stages, use this page to pick the dilution for each stage. {% hint style="success" %} **Dilute at least 1:100.** Most growth media are too conductive to measure at anything less dilute. If you get the error *conductivity too high*, use 1:201 or more as your lowest dilution. That is 50 µL of sample in 10 mL of diluent. {% endhint %} ## Pick your dilution
DilutionWhen to use it
1:100Lag, acceleration and early-exponential
1:1 000Mid- and late-exponential
1:10 000Deceleration, stationary, and decline
1:100 000 or moreHigh-density fed-batch fermentations
## Dilution schemes Every result inside the working range is accurate. Each dilution scheme on this page aims for about 1 × 10^6 cells/mL in the vial you measure. That gives fast results with little risk of clogging. ### 1:100 dilutions

A 1:100 dilution is a single transfer of 101 µL of culture into 10 mL of diluent.

Step by step, with videos {% stepper %} {% step %} ### Dilute 1:100 Transfer 101 µL of your [dispersed sample](/everyday-use/run-a-sample.md) into a diluent vial and [rinse the pipette tip](/more/how-to-guides/basic-sample-preparation.md) in the vial. Vortex for 10 seconds at maximum speed.
{% endstep %} {% step %} ### Measure Move the tubing kit to the 1:100 vial and press Measure. Multiply the result by 100.
{% endstep %} {% endstepper %}
### 1:1 000 dilutions

A 1:1 000 dilution takes two steps, 1:100 and then 1:10. Remove 1 mL of diluent from the second vial before you transfer 1 mL from the 1:100 vial into it.

Step by step, with videos {% stepper %} {% step %} ### Dilute 1:100 Transfer 101 µL of your [dispersed sample](/everyday-use/run-a-sample.md) into a diluent vial and [rinse the pipette tip](/more/how-to-guides/basic-sample-preparation.md) in the vial. Vortex for 10 seconds at maximum speed.
{% endstep %} {% step %} ### Dilute 1:1 000 Remove and discard 1 mL of diluent from a second diluent vial. Transfer 1 mL from the 1:100 vial into it and [rinse the pipette tip](/more/how-to-guides/basic-sample-preparation.md) in the vial. Vortex for 10 seconds at maximum speed.
{% endstep %} {% step %} ### Measure Move the tubing kit to the 1:1 000 vial and press Measure. Multiply the result by 1 000. {% endstep %} {% endstepper %}
### 1:10 000 dilutions

A 1:10 000 dilution takes two 1:100 steps.

Step by step, with videos {% stepper %} {% step %} ### Dilute 1:100 Transfer 101 µL of your [dispersed sample](/everyday-use/run-a-sample.md) into a diluent vial and [rinse the pipette tip](/more/how-to-guides/basic-sample-preparation.md) in the vial. Vortex for 10 seconds at maximum speed.
{% endstep %} {% step %} ### Dilute 1:10 000 Transfer 101 µL from the 1:100 vial into a second diluent vial and [rinse the pipette tip](/more/how-to-guides/basic-sample-preparation.md) in the vial. Vortex for 10 seconds at maximum speed.
{% endstep %} {% step %} ### Measure Move the tubing kit to the 1:10 000 vial and press Measure. Multiply the result by 10 000. {% endstep %} {% endstepper %}
### 1:100 000 and higher Extend the 1:10 000 scheme with a 1:10 step. Remove 1 mL of diluent from a third diluent vial, transfer 1 mL from your 1:10 000 vial into it, [rinse the pipette tip](/more/how-to-guides/basic-sample-preparation.md) in the vial, and vortex for 10 seconds. Repeat for each further factor of 10. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://help.sbtinstruments.com/more/how-to-guides/hit-the-right-concentration.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.