I Jerry rigged a scrubber with a deli container and barb fittings, but, look at the co2 scrubber lids on the fish of hex website and look at a small phosban reactor to make your life a little easier to n the install.
I’d also say the outside air may still be worth it, a 0.2ph bump is still substantial, but, you could try the scrubber method and see what you get.
Basically the outside air method is more work, but the co2 scrubber method would cost more, and has a recurring cost, but you could buy the co2 scrubbing media from BRS in bulk.