Short answer. Yes different brands of AL tanks have different buoyancy - anywhere up to +5lb when empty
As you dive outside the US, then you'll also find that manufacturers have different standards to meet local requirements. So brand X in the US might dive differently to that same brand in another country..
Trim is however for the most part, a factor of body position rather than weight position.
To give an example: I can dive my BC or wing, and use either rental AL's or my Steel HP 100 or HP 120 on either. I can also sling (or not) a AL 40 or Al 80. All I change is the quantity of weight required to be neutral (ish) at the end of the dive. If I'm teaching it's likely I'll have a weight belt maybe some additional loose weight in my BC pockets and the trims on my BC are low. On the other hand my wing (no plate) has trim pockets high up and I don't use a weight belt.
How ever I configure either of my sets, I can always hold trim. My point here is that the required weight needed is as you know a factor of how buoyant you and your kit are, and while some trim weight positioning may be required for say floaty feet (or neg /neutral fins) once you have that baseine dialed in you body can and will compensate for differing trim characteristics of that particular gear configuration
Remember trim positioning is done from the hips, and like riding a bicycle a bit of balance. Obviously this comes from practice and experience over a number of dives. Newer divers tend to "scull" - use their hands to maneuver until things start to click
In summary - don't mess too much with weight positioning once you're correctly weighted it shouldn't be too much of an issue.
Safe diving
As you dive outside the US, then you'll also find that manufacturers have different standards to meet local requirements. So brand X in the US might dive differently to that same brand in another country..
Trim is however for the most part, a factor of body position rather than weight position.
To give an example: I can dive my BC or wing, and use either rental AL's or my Steel HP 100 or HP 120 on either. I can also sling (or not) a AL 40 or Al 80. All I change is the quantity of weight required to be neutral (ish) at the end of the dive. If I'm teaching it's likely I'll have a weight belt maybe some additional loose weight in my BC pockets and the trims on my BC are low. On the other hand my wing (no plate) has trim pockets high up and I don't use a weight belt.
How ever I configure either of my sets, I can always hold trim. My point here is that the required weight needed is as you know a factor of how buoyant you and your kit are, and while some trim weight positioning may be required for say floaty feet (or neg /neutral fins) once you have that baseine dialed in you body can and will compensate for differing trim characteristics of that particular gear configuration
Remember trim positioning is done from the hips, and like riding a bicycle a bit of balance. Obviously this comes from practice and experience over a number of dives. Newer divers tend to "scull" - use their hands to maneuver until things start to click
In summary - don't mess too much with weight positioning once you're correctly weighted it shouldn't be too much of an issue.
Safe diving
