Product review (5 stars): Worth the money
Would love to know what the ingredients are for this additive, as I tried other alternatives and nothing worked.  I think this treatment is relatively cheap considering what the Venta  unit costs and found that one capful if this treatment is enough for the largest unit. My bottle from last year  is half full, so a bottle goes a long way obviously depending if you run this machine year round or just couple of months as in my case.
I usually change the water after every use rather than add water to the tank because the leftover water looks like dirty diluted milk...Other homemade solutions I tried made with vinegar, lavender, baking soda didn't work as I thought why bother with this treatment with my 10 year old machine. My homemade concoction started growing nasty algae like stuff if I forgot to clean the machine or stopped using it and cleaning became a chore. After buying my second Venta unit with the treatment solution as part of the package, it made me think of all the time I spent scrubbing the nasty goo growing on my previous machine was pointless. With this additive everything evaporates leaving behind a salt that comes off with hot water and a scrub sponge.  Not worth reinventing the wheel especially  when this treatment in readily delivered to my door and I don't have to drive to BBB to get it.