> 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/troubleshooting/other-problems/dilution-liquid-test-fails.md).

# Dilution liquid test fails

Your blank dilution liquid reads above the limits. Find the cause before you test again.

Your dilution liquid without any added medium or cells read above 30 000 cells/mL or above 100 000 total/mL. Do not just test again. Work through these steps in order, and stop when the test passes.

{% hint style="warning" %}
**Using your own dilution liquid?**

We cannot help you find the cause, unless we have set it up with you as a custom solution. [Contact us](https://sbtinstruments.com/contact) to talk about a custom solution.
{% endhint %}

{% stepper %}
{% step %}

### Replace the filter on the dilution dispenser

A used or faulty filter is the most common cause. Replace the 0.22 µm syringe filter mounted on the dilution dispenser, even if you replaced it this morning.

See [Replace the syringe filter](/more/how-to-guides/replace-syringe-filter.md).
{% endstep %}

{% step %}

### Use only SBT items

When the filter is not the cause, an item from another supplier usually is.

* **Vials.** Use SBT [empty vials](/item-register/individual-items/empty-vial.md), not your own 15 mL centrifuge tubes. Tubes from some manufacturers release particles into the liquid.
* **Disinfection liquid.** Use SBT [disinfection vials](/item-register/consumables/disinfection-vial.md), not your own 70 % isopropanol or ethanol. We have seen such liquids add particles that carry over into the next measurement.

Replace any item that is not from SBT.
{% endstep %}

{% step %}

### Fill vials on the day you use them

Do not fill vials the day before. Bacteria grow in a filled vial overnight.

Do not store filled vials in a fridge either. Cold storage changes the conductivity, and your BactoBox® will likely show errors.
{% endstep %}

{% step %}

### Clean with a fresh disinfection vial

Run <kbd>Clean</kbd> with a new SBT disinfection vial. A disinfection vial you have used for other things can carry particles over into the test.
{% endstep %}

{% step %}

### Test again

Have an SBT ready-made dilution vial? Measure it first, then run <kbd>Clean</kbd>.

Fill a new SBT empty vial with your dilution liquid and measure it. Do not measure the vial that failed again.

If the ready-made vial passes and your filled vial fails, the cause is in your liquid, dispenser, filter or vial.
{% endstep %}
{% endstepper %}

Still failing? [Contact us](https://sbtinstruments.com/contact).


---

# 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/troubleshooting/other-problems/dilution-liquid-test-fails.md?ask=<question>&goal=<user_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.