3/8, Must of been water, What is the most common way moisture gets in the system?
Great work! That basically what I was trying to build that as well, I took my old mkiii lid and cut off the dump port so I could just fill it in the 6x12 and set aside in dry ice over night the flip on to my 12x12 for recovery. I was going for something like the bhogart polisher for filter design. It looks like the use a 1.5" to 3" and then there 3" filter stack. What size filters did you use?
Butane absorbs water from the plant material. It absorbs less if you freeze the columns and use chilled butane.
You can remove it by inverting your tank and burping the vent valve after it sets for an hour or so at chilled temperatures, and by installing inline filter driers.