We are seeing a high proportion of HiSeq v3 High Output chemistry runs display very low cluster densities at the top of flow cells. The first couple of rows of tiles at the bottom of the flowcells cluster at normal densities whereas the top 4-or 5 rows of tiles on the top of the flowcell -- especially the top surface are very low.
By "very low" I mean below 60 thousand cluster/mm^2 on the top surface and below 300 thousand cluster/mm^2 on the bottom surface.
Quality doesn't otherwise seem to be impacted.
As of a month or so ago, we thought this was an issue with our cBot. But as of last week, tech support appears to be attributing all cases of this issue to reagents. Illumina is sending us extra reagents to compensate for the loss of reads. That is, we are running two flowcells to collect one flowcell's-worth of data.
Since both of our last 2 runs show this phenomenon, others must be seeing it as well. Anyone figured out a work-around that allows the normal cluster density to be restored?
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Phillip
By "very low" I mean below 60 thousand cluster/mm^2 on the top surface and below 300 thousand cluster/mm^2 on the bottom surface.
Quality doesn't otherwise seem to be impacted.
As of a month or so ago, we thought this was an issue with our cBot. But as of last week, tech support appears to be attributing all cases of this issue to reagents. Illumina is sending us extra reagents to compensate for the loss of reads. That is, we are running two flowcells to collect one flowcell's-worth of data.
Since both of our last 2 runs show this phenomenon, others must be seeing it as well. Anyone figured out a work-around that allows the normal cluster density to be restored?
--
Phillip
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