Housing buoyancy has been a problem for just about every photographer I've met, including myself. Compact strobes like the DS-125s pictured here are very compact, and thus very negative underwater. It takes air filled spaces to offset the negative weight of batteries, lenses, cameras, etc. When shooting wide-angle, the large diameter of a dome port will help offset some of the weight. ULCS and others also offer buoyant strobe arms of various lengths. The longer the arms, the more lift is achieved. This is all great for wide angle, and indeed, our wide-angle setup is close to neutral and a real pleasure to use. The opposite is true for a macro setup though - especially at night. You can see a typical night macro configuration in this picture -- swap the large wide-angle dome port for a compact flat port, long buoyant strobe arms for short ones, add a flashlight with batteries, and you can see how such a housing setup would be a real brick underwater.

I've tried a variety of methods to offset some of the weight. Cork, sealed in clear silicon, was a good contender, but it's life-span was limited (perhaps a few hundred dives) and affected resale value if it was glued to the strobe -- not to mention the warranty service issues. I could have used velcro and/or tie-wraps instead, but they would need to be removed and re-affixed every time the strobe was recharged. On our last trip I bought some watertight accessory cases from Trident, and used tie-wraps to suspend them from the strobes. You can see the setup with the accessory cases in the picture above. They provided almost enough lift, but were a bit of a hassle. They'd flop around above water, and would get in the way when handling the strobes underwater. I liked the idea of removable buoyancy "pods" though, so explored some of the possibilities.

For this trip, I've decided to use sealed 2" ID x 7.5" PVC pipe (two per housing). This is just a bit longer than the rounded accessory cases from Trident. Hopefully this will give me a little more lift, without making the whole "night macro" setup positively buoyant. To affix the PVC pipe to the housing, I've purchased some ULCS tri-clamps and flashlight adapters. The adapters were too small for the PVC pipe's diameter, so my father-in-law stepped in to make these aluminium replacements (seen in the foreground above). Once everything was sanded, I painted the floats and aluminium adapters flat black. You can see the finished product in the picture on the right. I should have photos of them in action on my return from Bonaire in a few weeks. I expect the tri-clamp + float system will work very well, although the length of the floats might have to be adjusted up or down to get a perfectly neutral setup. The pipes can also be replaced with longer or shorter models, depending on the configuration I'm diving. My goal at the moment is just to fix my night macro setup. The large dome port, and buoyant ULCS arms, help offset much of the weight when shooting wide-angle.

I'll post a comment with the results of my tests, on my return from Bonaire at the end of May...