These are the tank options I'm considering - which should I go with?

[rverma]

Hey, long time lurker, but first time poster.

I'm a new sidemount diver, but I have drank the kool-aid and I'm fully embracing it. I have the stealth tec 2.0 and currently dive sidemount mainly in cold water with a drysuit year round.

I don't own my own tanks yet but I'd like to get some so I can have them on hand and go diving on a whim, buy a reversed tank valve and permanently mount the tank bands. I know that steels are preferred for drysuit diving, but used steels are very hard to come by in my area (Vancouver Island, BC, Canada). Here are the options and associated costs in CAD:

1) Faber LP85 - $450 each new +tax
2) Faber HP100 - $500 each new +tax
3) OMS (Faber) LP 112 - $250 each. Made in 1999 but have current hydro and vis
4) Worthington HP X7-100 - slim chance to get them, found on facebook but owner hasn't replied. First and last hydro in 2011. I've read good things about these, would consider if sold for $250ish.
5) AL80s - freely available. I'm the equipment manager for my dive club and don't pay for tank rentals or fills.

In my lurking, I have discovered that the LP85s are the preferred option for their buoyancy characteristics. However, I like that the HP100 has the same diameter as the AL80s. The extra gas is a bonus as well. If I go with new steels, for an extra ~$50, I'm thinking "why not?" I'm not extremely concerned about the extra on-land weight of the LP112, but they have a diameter of 8" and I haven't found any instances where people have commented on their use for sidemount. They're mainly in the running due to cost, and that I could potentially fill them with a modest overfill (maybe 3000ish) myself if I wanted.

I don't mind spending money on new tanks, but saving money is always nice as long as it doesn't result in having to replace the equipment.

Are either of those used steels a good option? Should I spend money on new steels? Or just continue to use free AL80s?
Thanks!

 

[Bald Wookie]

Until this thread, I had not heard of LP72s. A quick search indicates they may no longer be in production, thus may only be available in used markets?

Honestly though, if you have free AL80s, just use those. The weight difference between 72s and AL80s is negligible in terms of bouyancy (1 or 2 lbs each).

If you want heavy steels that a different story, and honestly it depends on long term plans too. Planning to go cave diving in Mexico? I would recommend staying with AL80s to get used to the down clip and really ingrain it in your muscle memory. Only gonna sidemount in cold water? Do the heavier steels, likely HP100s if you aren't cave filling LP85s.

 

[inquis]

This [doing 2 dives off of a single fill of 2 SM tanks] kinda defeats the redundancy that sidemount divers want. I start my dive with 3000 in each tank, if I suck air at the same rate as the person I dive with, she ends the dive at 500 psi, and I end with 1750 in each. Do I really want to start dive 2 lacking that redundancy? sure, she could come up with 500, and me with 500 in each, but...
I'm an air hog. What is more typical is if we both dive singles, I come up with 500, and she still has 1200. With me sidemount, she comes up at 500, and I have 1200 in each. Now I can't do a second dive with her.

I don't see how you conclude the redundancy is lacking. As you say for the first example, you'd finish the second dive with 500 psi in each of your tanks, which is twice what you would have if you were on a single. That's clearly not lacking redundancy at the start of dive 2.

In your second example, when you know you will be doing 2 dives, why would you use more than half your air on the first dive? FWIW, a benefit of SM for 2 dives is that you can use that entire first half of your gas on the first dive. (The second half acts as a much larger reserve than you need.) Great, the first dive goes longer than it would have with you on a single.

As far as redundancy in that second/air-hog example, your buddy has one of your tanks all to herself should she need it (on either dive), which is plenty for her. Perhaps we are using that word "redundancy" differently.