I've put together a rig using an aluminum backplate, harness, cam bands and AL80 tank for minimalist diving. So far I've only used it in the pool. I'm wondering if it will be necessary to make/use a crotch strap in salt water. Most of what I've read is that when you surface with a rig like this that the AL80, when low on air, has a tendency to float up unless you use one. Anyone have some experience with this type rig and any suggestions? No, I don't want to buy a $teel tank.