If you're looking to add a cleaning solution to your carpet & upholstery cleaner, please note that it is extremely important to use the correct cleaning solution ratio. For the machine's 150ml water tank, the recommended ratio of cleaning solution to water is 1:20. 

To get started, simply add approximately 7ml of cleaning solution to the water tank. This is approximately equivalent to one bottle cap. Then, add water until the water level reaches the Max line indicator. Using the correct cleaning solution to water ratio will ensure that the cleaning solution is properly diluted and the carpet & upholstery cleaner is able to achieve its optimal cleaning performance during the cleaning process.