Product review (5 stars): Part of the routine maintenance for your Venta air washer and humidifier!
I am using an LW45 model of the Venta humidifier.  Every day I have to add about 1  to 2 gallons of tap water into the unit.  You do need treat the water with the Venta Airwasher water treatment additive and it takes 3.5 ounces of this liquid to treat the 3 gallons of water that the unit holds. You only add the treatment every 10 to 14 days and then you should dump the water and then clean the unit, refill it with three gallons of fresh water and add in the water treatment. The unit comes with enough of the treatment liquid to last you about 4 weeks. I ordered this bottle to maintain the unit in top operating condition.  It is 35 ounces so it is enough for 10 treatments or about 20 weeks.  I just set my smart phone to trip an alarm for me to clean the unit, change the water and add in the required 3.5 ounces of the water treatment additive.  I remove the water wheels and rinse them with fresh water.  I wash out the humidifier tub. I clean the fan assembly.  I refill the unit with 3 gallons of fresh tap water and then I add in this solution.  It really is simple and easy.

The cleaning fluid does the following things:
* It helps to maintain a hygienic environment
* It improves the evaporation process by making the water cling to the wheels drawing more water out of the reservoir to allow it to evaporate
* It prevents calcium deposits
* It prevents unpleasant orders

The front bottle label has graduations on it for every 3.5 ounces that you need to use.

This is a good product and it works well and I rated it at 5 stars.  I like the humidifying unit and I like that this cleaning solution does a good job keeping it fresh and clean.