Wendy, although I'm pretty sure I don't have your exact housing, I have several Ikelite (acrylic) and aluminum Aquatica housings. I also use a Nikonos.
The o-ring maintenence has been pretty universal and applies to every housing I've used.
Each housing has two sets of o-rings, user-maintainable and "permanent".
The "permanent" o-rings are the ones on controls and such. These I have the factory replace every year or two depending on use rates. Some are designed to be user replacable, but I've never taken a chance, and never had a flood from them either. If you ask nice they pressure test them after maintenence to make sure they actually will work.
The user-maintainable o-rings are the ones on the ports, back door, flash sync connections, battery plugs, etc.
The user-maintainable o-rings get the following every dive day: 1) remove o-ring from track 2)clean track with lint-free type of foam q-tip 3) inspect track for anything (especially hair) 4)lube o-ring 5) place o-ring in track 6)inspect again and 7)close housing.
On the same day, in between dives to change out film or CF cards, I just inspect carefully before closing.
The o-rings are lubed to allow them to move in their tracks under water pressure. This allows them to deform and seal. My only flood came from a hurry-up morning with no lube.
Keeping the o-rings on the housings and ports, for extended periods, forces them to take a set shape. This set shape is usually one that reduces the o-rings' ability to deform, and increases the chances of a flood.
So, o-rings used for diving should be removed when the camera is stored, to avoid taking a set.
However, storing a housing without an o-ring can allow impact damage to the o-ring track. So I use a set of "storage" o-rings. These are sacrificial o-rings that I place in the housings when not diving for more than a week or so.
The diving o-rings are stored in a ziplock baggie under the foam in the camera case lid. In the morning, just remove the storage o-rings and swap them with the dive o-rings.
If I'm on a trip, I just leave the diving o-rings in every day. I also have a set of new o-rings along, just in case an o-ring gets nicked or damaged.
I personally leave the housing open to ambient pressure when flying. They are designed to hold pressure out, not keep it in, and control glands may become displaced (read: flood) or other subtle problems may occur. I just don't take the chance. In fact, the port and body caps for my Aquatica come with a hole drilled in them to allow the housings and ports to equalize.
Whew! Alot there, probabally more than you wanted. Just keep in mind there's alot of ways to do this housing stuff. This has worked well for me.
All the best, James
