# Troubleshooting running low diversity samples with low PhiX spike in on the iSeq 100

The iSeq 100 uses one-channel chemistry. To obtain high-quality data on an iSeq 100 for low-diversity libraries, a spike in **at least 5% PhiX**. This will increase the amount of signal in channels with lower signal in each cycle and help to balance the base diversity, resulting in high-quality base calls.

For further information, search for Knowledge Base article **How much PhiX spike-in is recommended when sequencing low diversity libraries on Illumina platforms?**.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #1369), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000001369%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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