# Time of running DADA2

**URL:** https://forum.qiime2.org/t/time-of-running-dada2/7769
**Category:** Technical Support
**Tags:** dada2
**Created:** [January 10, 2019, 11:09am UTC](https://forum.qiime2.org/t/time-of-running-dada2/7769 "2019-01-10T11:09:41Z")
**Posts on this page:** 1
**Showing post:** 26

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### Author: ![Nicholas\_Bokulich](https://forum.qiime2.org/user_avatar/forum.qiime2.org/nicholas_bokulich/32/19937_2.png) [@Nicholas\_Bokulich](https://forum.qiime2.org/u/Nicholas_Bokulich)
#### Post date: [January 15, 2019, 2:50pm UTC](https://forum.qiime2.org/t/time-of-running-dada2/7769/26 "2019-01-15T14:50:55Z")

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Thanks @ucassee. Could you please also provide me with the command that generates this error with these sequences? Please also send the QZA.

> [@ucassee](#):
>
> i still don’t understand why dada2 can’t be used to denoises joined reads.

> [@Can DADA2 be carried on pre-joined reads](https://forum.qiime2.org/t/can-dada2-be-carried-on-pre-joined-reads/7269/2):
>
> Hi @sindhu_mohandas, No actually, Dada2 will not perform properly if your reads are pre-joined with another tool. The main issue is that this is in conflict with the error-building approach utilized by Dada2. When you join reads you are assigning new quality scores (calculated differently between different tools) in the overlapping region which are not true q-scores which Dada2 uses. So, you want to run raw data without any prior modifications. What you've done is more appropriate for Deblur h…

[https://github.com/benjjneb/dada2/issues/327#issuecomment-400038014](https://github.com/benjjneb/dada2/issues/327#issuecomment-400038014)

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