RE the flooded compartment, I like the half-sunken equipment and floating barrels idea. The whole project is simply breathtaking and wonderful, best of it's type I have ever seen; so glad you didn't abandon it and get rid of your original corridors.
Thanks everyone. The floating barrels is all me trying to channel half-life, and the sunken depth idea is to try and give the illusion of much greater depth than the ~12mm max depth limitation that the corridor height creates. I'm going to do the "water" very opaque, as per the new orleans power plant photos.
I'd love to get an estimate on how much time it took to build this latest tile!
Well, the first pic I have in my image stream for this:

Was posted three months ago. I figure I've probably spent an average of about 10hrs a week on it, so I guess ~120hrs. That's not exactly been very efficient though, because a large part of my build time is just thinking through the engineering problems and dry-fitting, and in this case ripping up and re-doing once (you can see many of the concept elements in that pic aren't in the final build). I'd say I spent about 50% of my time like that, so if you had an actual plan maybe 60hrs? Now that I've worked it out it seems terrifying.
Other numbers: this room used 1 full strip of green stuff, 25g of poly cement, and about £50 quid of materials.