I've gone on several night dives and it is my favorite type of diving. First time out I figured that my buoyancy would not change just becouse I was diving at night. So I used the same weight that I used on the daytime dive. I carry just enough weight that I will sink just a little when at the bottom. That way I can (hopefully) maintain neutral buoyancy when doing a safety stop at 15-20 feet with no or very little air in my BC. With a 3mm suit that comes to about 14 pounds at this stage of the game. Anyway it hasn't been a problem for me while night diving. I don't try to take any pictures or anythig while doing the night dive. I let the other divers go through that and keep the pictures in my memory. This leave me time to just observe the surroundings and keep an eye on the other divers so I don't get lost. Works for me.