We recommend that you open your spa cover regularly to allow chemical vapor to evaporate. This will help keep the cushions, cover, and waterfalls/fountains in good condition. Ideally, you should leave your cover open for 30 minutes a day. Here are some interesting links to help you with your spa maintenance!
https://www.trevi.com/en/tips-and-advice/tips-and-tutorials/spa-maintenance
https://www.youtube.com/watch?v=WRc-YEAcW9E
https://espaceclient.trevi.com/detaillants/papeterie/Guide-entretien-SPA-EN.pdf
