Vacuum in backwash position

[yukikito]

Hello! We are new pool owners so as a precaution, we hire a pool cleaning service. Today, I saw them vacuuming the pool while the multiport was in the Backwashing (and after rinsing) position. Isn't this a big no no?!
Thank you in advance for your input!

 

[Paladi]

Sounds like a big no-no, indeed... I'm a noob, but if I'm not mistaken this will build up the debris from vacuum at the exit side of your filter, and when you start again in filtration mode it will pump all the debris back to the pool...

 

[LBI salt pool]

My be pool installer told me it was ok to vacuum to backwash when I’m lowering my water volume after a big rain. He said you kill two birds with one stone….drain pool and get a free backwash too