Best solution is to add enough vents to get adequate oxygen to the tank.
Based on Peggie's book / recommendations I was successful on previous boat.
On current Mainship I had to add a bubbler as access to add / modify vent was next to impossible. For dsetails see the "Projects" section at
"Bacchus" website
I'm sure the Groco Sweat Tank would work but at close to $300 I felt the DIY approach was worth a try - 3rd season and it works well. I did replace the copper bubbler tube w plastic this season otherwise it is still working fine.
I agree w/ Peggie that the charcoal filter approach causes more problems than it solves but some are very happy using the approach.
I'm also a NoFlex believer thanks to recommendations from others here on tf.