Adjusting weight for going from AL 80s to AL 100s?

[HungryFrog]

I am going to be trying some aluminum 100 CF tanks on my next dive and was told they are more bouyant compared to the 80s, anyone know if it is enough of a change to where I may need to add weight?

I was going to drop 2#s before my next dive, but will probably hold off for now, I'd rather go down too easily than be a dork cork.

[delsol]

That is a question that requires a little more information.  Every brand builds tanks to their own specs.   Here is a good reference for tank specs: http://www.tdl.divebiz.net/pub/tanks.html . 
The difference between the empty bouyancy of the tank you were using and the one you plan to use is the approximate weight you should add or subtract.
example1:
luxfer 80 to catalina c100
(4.4)-(-0.4)=4.8 lbs. heavier, so you can remove 4.8 lbs.
example2:
luxfer s80 to luxfer 100
(2.26)-(3.11)=-0.85 lbs. lighter so you may need to add 1 lb.

Hope that helps more than it confuses, and welcome to the board.

[HungryFrog]

Ok thanks.  I checked and they all are luxfers.

As for the weights, I was going to drop two pounds before my next dive, now I will try these tanks first and not change anything weight-wise.