Hi, My name is Robert i own a commercial diving company in the Houston, Texas area. We work in Dark water or Zero Vis. water on a daily basis and believe me i wish it wasn’t so!!
Years ago when we started doing underwater inspections in the Houston Ship channel we could only do them by feel or touch. We had noway to video what we were inspecting to share with the clients so i built my first Clear water box for my underwater CCTV/DVD system 15 designs later i have a system capable of taken detailed full color pictures in Zero vis waters. The Basic explanation for how it works is you have a box with one open end clean water is pumped into the box from the surface into the closed end opposite the open end the clear water fills up the box pushing out the dark water you can position the box in front of the object you are wanting to video and wait a few seconds the clear water will push around the object allowing it to be seen by the camera. but believe me its not that simple there was a lot of trail and error before we developed a box that worked with the efficiency that was required for timely inspections. I do custom builds on a limited basis for fellow divers each one is unique to the camera being used. Is this the info you was wanting, let me know!
Best Regards Robert SEMPER FI !!!!!!!!!