Here's what I've figured out so far between SM diving in Canada and Mexico.
Two systems of SM.
1. Designed for tanks which float when near empty.
2. Designed for tanks which stay negative and behave as ballast.
The easy way to use system #2 with al80s is make them negative by adding weight. (Ideally streamlined and well attached.) Otherwise you need to modify the BCD harness to look like system #1.
When I switch between lp131s and al80s the same day with a #2 I add lead to my tanks. When I dive al80s for months I use a #1 style setup.
Where #1 style harness configuration is rare people still add lead.
Do what works.
Cameron (A pretty ugly, starting to be experienced, SM diver)
Two systems of SM.
1. Designed for tanks which float when near empty.
2. Designed for tanks which stay negative and behave as ballast.
The easy way to use system #2 with al80s is make them negative by adding weight. (Ideally streamlined and well attached.) Otherwise you need to modify the BCD harness to look like system #1.
When I switch between lp131s and al80s the same day with a #2 I add lead to my tanks. When I dive al80s for months I use a #1 style setup.
Where #1 style harness configuration is rare people still add lead.
Do what works.
Cameron (A pretty ugly, starting to be experienced, SM diver)