Catalyst eruption

[pipecreekline]

Using my catalyst fermenter for the first time. On the second day of fermentation I went to change the jar underneath. Everything was great until I opened the valve on the new jar. A geyser of beer blew off the airlock and a gallon of wort went all over the place! What did I do wrong?Do I need to remove the lid or the airlock or just go super slow with opening the valve? Thanks for any help.

 

[whovous]

My practice was to go slow, but lately I've made some pretty high gravity brews, so I fill the jar with RO water before opening the valve. If there is no air in the jar, there can be no burst of air in your fermenter. Also, the less oxygen you add to fermenting beer, the less oxidation you will have to deal with later.