Hi
There seem to be various ways to install an vacuum lock on your UW housing. The vacuum lock is meant to create a underpressure (or: small vacuum) of around -5 Hg. Which equals .16 Bar: that is the pressure of a water column of around 2 meters. ScubaCam in Holland sells a simple and relative cheap device which includes a VacuVine pressure pump and a stainless steel one-way valve that can be screwed in one of the function buttons on the Ike housing you dont use (like the Fn button in front). I found it very simple to install and effective. After 15 pumps (or rather: 'sucks') the vacuum is installed and it will be difficult to remove the port or back lid. A vacuum gauge is not really necessary..but if you happen to have a gauge (or small barometer) you could place it inside the housing (like I did) to check the vacuum and if it remains stable.
