@Lasse
Are you not at all worried about the product being made with brass (metal) and having the air run through it? Also, I know that ones that come out of China may not be regulated in the exact alloy that is being used.
From my other reading of this forum I found a group of people that bought a 3/8in push connect air solenoid that can be either AC or DC and either in always open or always closed positions (depending which you need more often). What that person did was use a Y adapter that connected to the skimmer intake. From one part of the Y it was connected to the CO2 scrubber. The other part was connected to the solenoid and a short tube that was just in the stand. The solenoid was always closed, unless energized. Because air follows the path of least resistance when the solenoid is closed, the air would draw through the scrubber. The solenoid was programmed to open if ph would hit let’s say 8.25, and again, since air flows theough less resistance, it would go through the short tube, bypassing the scrubber. This way you would also need only a single switchable outlet.
As a side note, the air may draw a little bit still from the scrubber, but that can be either adjusted by having the solenoid open a bit earlier, or placing another solenoid on the scrubber line that is opposite the other valve closing the co2 scrubber entirely.
https://www.mcmaster.com/#5489t493/=16x9f57 this is the DC version of the solenoid that takes a 24V DC connection.
https://www.bulkreefsupply.com/ozone-resistant-kynar-y.html and the various sized tube adapters.
I believe they used the 3/8in since that is the most common size connector for the skimmer and also the size that the BRS scrubber uses
What are your thoughts on that set up?