LP or HP tank?

[Vtach]

If you are strictly looking for a single steel cylinder, you probably won't find a whole lot that have 130 cu ft at low pressure (2400).  The largest LP cylinder that is readily available are the 120's.  That leaves you only HP if you are dead set on 130 cu ft.  I prefer doubles and would recommend that you also have redundant regulators (1st and 2nd stages) if you are looking to extend your range and time safely for either doubles or a single.  Small size doubles like 72's or 80's are great for a start.  They are also reasonably priced and you might just find a used set of small doubles cheaper than a single new LP 120 or HP 130.

I guess the biggest things you may want to consider is exactly what depths you are planning, what your gas consumption rate is.  Once you have those things calculated you can run some mock dives and see what your gas needs are to safely complete the dive.  Based on that information, you may only need a stage or you might need double 130's AND a stage ;D.

Here's a link to help anyone out with calc's.