# Using DADA2, losing 50% of reads after filtering and 80% of reads by the end

**URL:** https://forum.qiime2.org/t/using-dada2-losing-50-of-reads-after-filtering-and-80-of-reads-by-the-end/12745
**Category:** User Support
**Tags:** dada2, filtering
**Created:** [December 4, 2019, 8:44pm UTC](https://forum.qiime2.org/t/using-dada2-losing-50-of-reads-after-filtering-and-80-of-reads-by-the-end/12745 "2019-12-04T20:44:54Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![FrancineMarques](https://forum.qiime2.org/letter_avatar_proxy/v4/letter/f/6bbea6/32.png) [@FrancineMarques](https://forum.qiime2.org/u/FrancineMarques)
#### Post date: [December 4, 2019, 10:00pm UTC](https://forum.qiime2.org/t/using-dada2-losing-50-of-reads-after-filtering-and-80-of-reads-by-the-end/12745/2 "2019-12-04T22:00:44Z")

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Hi Andrew,  
I would love to know the answer for that too - we are having similar issues with faecal/caecal samples using the EMP protocol to the detail with V4-V5 primers (example below). Which protocol are you using for your library prep?

 ![image](https://forum-qiime2-org.s3.dualstack.us-west-2.amazonaws.com/original/2X/2/2d481d02a524c7d2a8c5b8a2afa7503c7cf0cc59.png)

Sorry I don't have an answer (yet), we are currently running some tests.

Best wishes,

Francine

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