Co2 scrubber question

[tmo65]

Question for the group. I have a reef octo co2 scrubber attached to my reef octo protein skimmer. It is set up as a recirculating system. What is the purpose of the extra intake /valve on the co2 scrubber? Is this the new intake for the whole system? Should it be open or closed? Also, would it help raise my ph if I attached a second hose from this to the second intake on the protein skimmer?

 

[TBSB2019]

It should be closed. If ph gets to high you can crack it open to lower/stabilize it.