Hi Peaker,
There are a couple of things that are important.
- First and foremost is tht the mask fits you. You can check this with the "vacuum" seal test. Turn the strap around so it's on the front of the mask and then put the mask up to your face like you would if you were wearing it normally. Then suck the air out of the mask. Don't do this forcefully, just enough to make it stick to your face. Then hold your breath and let go of the mask. If you can count to 5 or more slowly before it falls off your face then your mask fits. If the mask doesn't fit then you'll never get it water tight.
- Second point is to not tighten it too much. It's natural to think that if it's leaking that it's too loose. In fact the water pressure alone will hold the mask on your face for the most part. The strap should just give you light tension, not forcefully pulling the mask onto your face. If it's *too* tight then you can pull the seal out of shape and it will leak, even if it passes the vacuum test.
- The third bit about the facial hair is something I can really relate to. I also let my beard grow and it does make any mask leak. the good news is that you *can* find masks that will be better than others. I've found two over the years that work for me One is a Tusa Look and the other is a no-name mask with the internal volume of a small submarine. What works for you won't be what works for me but keep looking and don't look at the price. A mask that fits ... fits. If it costs $20 or $100.
The one thing you can do to get a slightly leaky mask to seal with a moustache is to put a layer of Vaseline on your lip. It's messy but it works.
Good luck.
R..