# To remove primers and spacers or not? - Zero usable reads after DADA2

**URL:** https://forum.qiime2.org/t/to-remove-primers-and-spacers-or-not-zero-usable-reads-after-dada2/11680
**Category:** User Support
**Tags:** dada2, primers, cutadapt
**Created:** [September 26, 2019, 2:47pm UTC](https://forum.qiime2.org/t/to-remove-primers-and-spacers-or-not-zero-usable-reads-after-dada2/11680 "2019-09-26T14:47:29Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![ben](https://forum.qiime2.org/user_avatar/forum.qiime2.org/ben/32/1790_2.png) [@ben](https://forum.qiime2.org/u/ben)
#### Post date: [September 26, 2019, 2:58pm UTC](https://forum.qiime2.org/t/to-remove-primers-and-spacers-or-not-zero-usable-reads-after-dada2/11680/2 "2019-09-26T14:58:44Z")

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> [@Dada2 denoise-paired removing most sequences during filtering](https://forum.qiime2.org/t/dada2-denoise-paired-removing-most-sequences-during-filtering/7159/2):
>
> Hi @FrancineMarques, Thanks for searching through the forum first and providing us in depth detail about your situation. Really helps with the troubleshooting! This is a common enough scenario so let's take a closer look. Your dada2 stats summary show that your major loss occurs at the initial filtering step. Denoising/merging etc all look good! So, moving backwards one step, looking at your demux.qzv quality plots, it looks as though your reads are unfortunately not high in quality. There is …

Maybe this can help? it looks like you have sequences on input, but the quality plots look suspect. Is there proper overlap between the forward and reverse reads?

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