I simply add 3L of water to a 5L empty water bottle like this one
Click to view attachment then i add 1 tablespoon of mollasses and bubble for an hour or 2 at between 30-35c.
Then after the hour or 2 i add 3-5ml of catalyst along with 5-6g of essence and bubble for 12 hours keeping the temps at around the 25-35c.
After the 12 hours its always nice and frothy so i know its worked so i simply add another 5-10ml of catalyst then i add 4.5ml of bio-wetter and thats us ready to get spraying.
For me it was easier to do it this way as i couldn't bubble the 2 different lots of water at the same time like the way pro lib did his and i'm pretty sure i seen OT1 do the same or similar to way i do it a while back, only difference i think was it was an old 5L bio-bizz bottle, could be wrong though maybe i'm thinking of something else