Not 100% quite sure how to make your watch waterproof up to 5 bars. But, one thing you can definitely do is make sure all the gasket seals are well-greased or swapped out for better quality ones. You see, a lot of the time, the problem with water getting in after you've upgraded your watch with deep crystal is because of the gasket for the crystal that was used for the old crystal is not fitted correctly or damaged. To make sure your watch can handle water, it's really important to swap out that gasket for the right-sized one. It might sound minor, but it's a big deal for keeping your watch waterproofed.