Is it the BCD or some screwy buoyancy issue?

[ScubaJE]

Take a closer look at the tanks she is using. Some AL 80s are 4#s positive when empty (Luxfer 80), some are slightly negative (Catalina C80)

See this post for the lowdown.

Updated SCUBA tank specifications list -- in PDF and spreadsheet

Hello! I have wasted my entire d1ay re-working a SCUBA tank specifications list. I've been working with the Huron Scuba list for *years*, but I'm suspicious of the information: where did it come from? Also, it includes a lot of junk I've never seen in real life, as well as tanks that no one...

scubaboard.com

I will check this, thanks! The issue occurred mostly with tanks from two dive shops, so that could be interesting...

 

[Angelo Farina]

Take a closer look at the tanks she is using. Some AL 80s are 4#s positive when empty (Luxfer 80), some are slightly negative (Catalina C80)

See this post for the lowdown.

Updated SCUBA tank specifications list -- in PDF and spreadsheet

Hello! I have wasted my entire d1ay re-working a SCUBA tank specifications list. I've been working with the Huron Scuba list for *years*, but I'm suspicious of the information: where did it come from? Also, it includes a lot of junk I've never seen in real life, as well as tanks that no one...

scubaboard.com

This is the only sensible explanation.
Tanks seems all equal, but they are not...
I and my wife own two "identical" twin sets, called Aralu, made of a pair of Luxfer tanks, 9 liters each.
My ones weight 10.7 kg each, my wife's are 10.3 and 9.8, so in total her tanks are 1.3 kg lighter than mine...
Same brand, same year (1973), same capacity, different weight.
Here the law mandates to engrave both capacity AND weight on each tank, so when you rent them you can adjust your weights.