Please, define your perfect Sidemount gear

[Patoux01]

I have zero experience of the LP tanks. In the civilised world we use 207, 232 or 300 bar tanks. All the steels are negative throughout.

I'm not sure... Some 12l tank weigh 12.2kg, so they'll come pretty damn near being positive and I would suspect they behave like crap on rails.

 

[Darghu]

Yea sorry I know that a lot of you guys are located in USA this is kinda annoying to speak about UE regulations
I would have no problems at all about tanks but this is the filling station:
- they don't want to fill if it's not UE regulation
- they don't want to fill if it's not correctly got inspection / hydro
- some prefer to fill only tanks registred to the federal things - inspection / hydro
Well I' have no idea but some issues can be fixed if I own a home filling station.

 

[MichaelMc]

I'm not sure... Some 12l tank weigh 12.2kg, so they'll come pretty damn near being positive and I would suspect they behave like crap on rails.

OP, using tanks that are regulatory wise blessed for where you are is about the only sensible way.

Now that I've mucked up the issue.
Faber makes tanks with US regulatory approvals that have low pressure (2650 PSI / 183 bar) and are positive when empty, such as 13l / ~80 cu ft are 2.3 lb. / 1 kg positive empty. You might have low ish pressure steel tanks, that also go positive. So the steel == rail, aluminum == movable clip off, might more be always negative == rails, others == movable clip off. With some vague transition point between the two when the bottom gets floaty. Here those tanks, LP80, are preferred for small ish warm water sidemount when you do not need extra negativity. Which is why I asked.