Ozone plug open-close

[Giulio]

Hi everyone!
I have a Bubble King supermarine 250, on my skimmer pump I have two plug, the first air plug and second ozone plug. I use this pump with ozone plug open!
what could change holding closed it? or is the same thing open or close?
THANKS!!

 

[Giulio]

Nobody say something?

 

[Anthony kolodziej]

don't think it really matters leaving it open just allows more air to the skimmer closed I don't think it makes much difference