Which tank to buy?

[Tomeck]

Well, I'm diving with a steel, period. I hate aluminum.

I'm aware of the buoyancy characteristics...that's why I want a steel. So you're saying LP is a better investment, basically?

Why you hate aluminium? It is very good for the protection against corrosion.

 

[Jack Hammer]

I prefer HP tanks. These are how much air you get at different psi for Worthington tanks. If you compare the physical size and capacity of HP vs LP tanks, you'll find that a HP119 is about the same physical size as a LP95. At the lower fill pressure you get the same amount of air. But a HP is rated for higher pressure. You don't have to overfill it, you can use the HP as a LP, but safely pump it up for when you need more air.

Cylinder.............2640 psi........3000 psi.........3442 psi
X7 Steel 80........64 cu. ft........72 cu. ft........80 cu. ft.
X7 Steel 100.......80 cu. ft........89 cu. ft.......100 cu. ft.
X7 Steel 120.......96 cu. ft........107 cu. ft......120 cu. ft.
X8 Steel 119.......95 cu. ft........107 cu. ft......119 cu. ft.
X8 Steel 130.......104 cu. ft.......117 cu. ft......130 cu. ft.

I just bought a HP100 to replace my AL80. If I get a crappy fill of 2800psi, I still end up with ~10cf more air than the same fill in an AL80. I can use it as an 80cf or if I need 100cf.

For your original question. For two dives on one tank, you'd probably want 100cf of air at a minimum. It really depends on how long you are planning each dive to last and your consumption. Don't forget to factor in a safe reserve amount.

Jack

 

[Skeeter1097]

I dive steel and I Have lp and pump them as needed.Mostly 108 lp at 3000 is where I am . But if I am going deeper of on wrecks I have pumped them to 3600. That is some serious gas.

 

[emttim]

Since you have less than 50 dives under your belt, this is the tank you should get:

-None of the above.

You really need to do some more diving and figure out exactly what you want to do. Will you be diving on vacations? Warm water? Cold water? Do you want to move into Technical diving?

Until you have a good idea of what you want to do, any advice on which tank to buy is premature and ill-advised.

You're getting a lot of recommendations from experienced divers who like something for a particular reason. There's nothing here to suggest that their reasons are in-line with yours.

Tanks are way cheap to rent so keep doing that until you really know where you're going with this sport. I'm fairly certain that if you leap out and buy a tank now you'll end up abandoning it fairly soon.

-Charles

Maybe it was different for you, but I have a perfect idea of what kind of diving I plan to do, and I didn't need X amount of dives to learn Y skill. I'm so sick of this mantra that's repeated over and over. I wonder if the people who subscribe to it really believe that bull**** that you suddenly know enough about a certain topic after a specific number of dives. Please don't make me vomit in my mouth.

Fact of the matter is, I do a significant amount of shore diving in Monterey which is within driving distance, hence transporting a tank is preferable to renting since I don't have to worry about getting a tank through airline baggage (which I wouldn't attempt because it'd be too much of a PITA), and will be cheaper as well as more cost effective since I will not be driving to a dive center in Sacramento to rent the tanks and then driving back to that dive center to return the tanks. I will live 20-30 miles from Sacramento in a month and I currently live about the same distance. With gas at 4.19/gallon here for premium (what my car requires) and rising, you do the math. The cost of gas as well as rentals adds up fast.

What I don't do in shore diving, I do in Channel Islands liveaboards. All the boats that I plan to use, as well as the one I already have used, do not provide tanks so I need to rent them anyway. At best, I may get close to the tank that I want, but more than likely I may get stuck with a LP steel or an aluminum which puts me at a disadvantage.

I also plan to start the Divemaster program this summer and will be doing pool sessions with Open Water classes so having my own tank will be a lot easier for that as well. I already know precisely where I plan to go in diving. Making assumptions to the contrary isn't going to get us anywhere.

I'm fairly certain if I heeded your advice, I would sorely regret it, but I do appreciate it nonetheless if that makes any sense.

...with the counter argument that Tanks are one of the few things in Scuba that seem to hold some value. If renting tanks is keeping you from getting in the water (due to time constraints, or availability) than owning any tanks is better than none. And an investment in a steel tank will probably end up costing you very little should you decide to trade up for a different size next season.

I don't buy the "only good if you can get the pumped to 3500" argument for the steel tanks. Check the charts and see how they're rated. Worst case is you might sometimes have less gas, but in the event that a full fill is available you get the benefit.

We bought tanks with about 10 dives under our belts. It meant that we got to dive about twice as much as we would have otherwise due to not making a weekend dive into a 3 day process of picking up tanks, diving, then returning them on monday, causing one of us to be late for work. We went HP 80's since the buoyancy characteristics were nice, and the cost (after some negotiation) was not much higher than AL80's. HP 100's would be nice (and my first choice), but the cost difference meant we could get 4 HP 80's or two HP100's. (buying for two people, gotta keep things "even", so no, the cost was not half...)

Still though, see what tanks your local shops rent and try as many of them as you can if it's reasonable to do so. And, don't underestimate the power of being ready to buy - being in the shop and saying "make me an offer I can't refuse" can shake out some deals if you're in the right place at the right time. They might be looking to move a couple of thanks that have been sitting around for a couple of months, or adding a couple more to an impending order that will give them a price break.

Sound advice. If I could get two HP 80s for the price of one HP 100, then I would certainly do that instead as I am already weighted for steel 80s anyway so it would be a hassle-free transition. The assumption that I would be diving a lot more if I owned my own tank is quite accurate; not having to deal with the pain in the ass of renting a tank and then returning it every time I want to go diving is gold to me.

Why you hate aluminium? It is very good for the protection against corrosion.

Right, I'm aware of the corrosion issue with steel, which is why I plan to take very good care of it. I hate aluminum primarily because of the buoyancy characteristics. I absolutely hate the buoyancy that an aluminum provides (or doesn't provide as far as I'm concerned). Any tank that has a tendency to shove your face forward and into the water constantly at the surface because it's positively buoyant when empty will always get two thumbs down from me. Sure, I could solve that problem by adding some weight to the tank itself, but why would I want non-ditchable weight to jimmy rig a fix to a problem I could avoid completely by getting steel?

I prefer HP tanks. These are how much air you get at different psi for Worthington tanks. If you compare the physical size and capacity of HP vs LP tanks, you'll find that a HP119 is about the same physical size as a LP95. At the lower fill pressure you get the same amount of air. But a HP is rated for higher pressure. You don't have to overfill it, you can use the HP as a LP, but safely pump it up for when you need more air.

Cylinder.............2640 psi........3000 psi.........3442 psi
X7 Steel 80........64 cu. ft........72 cu. ft........80 cu. ft.
X7 Steel 100.......80 cu. ft........89 cu. ft.......100 cu. ft.
X7 Steel 120.......96 cu. ft........107 cu. ft......120 cu. ft.
X8 Steel 119.......95 cu. ft........107 cu. ft......119 cu. ft.
X8 Steel 130.......104 cu. ft.......117 cu. ft......130 cu. ft.

I just bought a HP100 to replace my AL80. If I get a crappy fill of 2800psi, I still end up with ~10cf more air than the same fill in an AL80. I can use it as an 80cf or if I need 100cf.

For your original question. For two dives on one tank, you'd probably want 100cf of air at a minimum. It really depends on how long you are planning each dive to last and your consumption. Don't forget to factor in a safe reserve amount.

Jack

My SAC rate is about 0.63 cubic feet per min. I figure I can get around two 30-minute dives at 33 feet with an air fill to 2500 or 3000 with a HP 100. Most of my dives are around half an hour anyway because my dive buddy chews up air a lot faster than I do and/or we see all that we want to for that dive. I figure if I do a dive that's really incredible and I use up all my tank's air, then that's fine, if the dive was that great then it'll be worth it to go get an air fill after one dive. Plus the extra margin of safety for deep diving will definitely sit well with me. And yes, I factored in 500 psi of reserve air into those figures I mentioned above, however, on a deep dive I would probably factor in a reserve of 800 to allow time for a mandatory safety stop. Hell, I might do 1000 psi for a reserve just to be safe the first few times until I get used to how much air I consume at X depth.

Thanks for all the advice guys, I really appreciate it. After reviewing this thread, the articles/links offered, and my instructor's recommendations, I think I'm going to get a HP 100 and have it Nitrox dedicated. I don't necessarily dive a particularly aggressive profile, but on the other hand, nitrox will allow me to maximize the amount of diving I do in one day due to lesser nitrogen absorption even when you take into account oxygen absorption as well. The opportunity of having either more dives in one day, or longer dives at depth, far outweighs the extra few bucks for a nitrox fill and the extra cost to get it set up. If I want to dive air, I can get an EANx21 fill and it's physically the same thing. If I want to dive nitrox, instead of having to go and rent a tank anyway, I'm already good to go.

 

[BKP]

Thanks for all the advice guys, I really appreciate it. After reviewing this thread, the articles/links offered, and my instructor's recommendations, I think I'm going to get a HP 100 and have it Nitrox dedicated. I don't necessarily dive a particularly aggressive profile, but on the other hand, nitrox will allow me to maximize the amount of diving I do in one day due to lesser nitrogen absorption even when you take into account oxygen absorption as well. The opportunity of having either more dives in one day, or longer dives at depth, far outweighs the extra few bucks for a nitrox fill and the extra cost to get it set up. If I want to dive air, I can get an EANx21 fill and it's physically the same thing. If I want to dive nitrox, instead of having to go and rent a tank anyway, I'm already good to go.

Sounds like a plan. You'll enjoy the HP 100.

Keep one other point in mind, in terms of an EANx dedicated tank. You'll still have yearly visuals, so you'll have to add O2 cleaning to that annual bill as well. However, if you're willing to eat the added cost of Nitrox every dive, the O2 cleaning shouldn't be an issue.

Good luck, and dive safe...

 

[zen_man]

emttim, I think the HP 100 is an excellent choice you will not regret. And, nice post. Now let's go diving!

 

[D_B]

Had 18 dives when I purchased a Worthington HP100 , love it and I will not go back to an alum tank (if I can help it)
I like the smallness/weight of the HP100
yep, on one boat I only got 3000psi, but that's still more air than my old al80, and the other boats I dived here have no trouble in filling it to 3500psi

 

[emttim]

Well, went to the dive shop and purchased the HP 100. After the green nitrox cap, the tank itself, the contents tag, the nitrox decal sticker and sales tax, it came out to $372.11. I figured that's about what it'd cost...he said it'd be ready tomorrow to pick up, but since I work, I'm just going to pick it up next Friday when I pick up my tank rental (going to have 2 tanks period to be on the safe side for rescue diver class) for my rescue cert dives not this weekend but next. Unless of course I can actually get ahold of my dive buddy to do a few dives before rescue to get my weighting down. The only thing I dislike is the fact that a SSI nitrox decal is being put on it since the dive shop I bought it from is SSI and not PADI, but I honestly don't give that much of a crap which agency's decal is on it...just a minor annoyance since I don't want people bugging me when they see the tank and assuming I'm an SSI diver and asking me about it.

I'm actually surprised at how small and short the 100 is, I was expecting it to be a lot taller, which is great since it'll make it a lot less of a PITA to use. I'm guessing the weight is going to be noticeable, but oh well, it'll be worth it.

emttim, I think the HP 100 is an excellent choice you will not regret. And, nice post. Now let's go diving!

Hey, send me a PM if you can dive the 29th and 30th...I need to get my weighting down for the 100 anyway!

 

[spectrum]

Well, went to the dive shop and purchased the HP 100.

Regardless of what you take for a path that's an excellent cornerstone to your collection.

 

[BKP]

I'm actually surprised at how small and short the 100 is, I was expecting it to be a lot taller, which is great since it'll make it a lot less of a PITA to use. I'm guessing the weight is going to be noticeable, but oh well, it'll be worth it.

emttim, since a standard AL80 is only about 1-1/2 lbs. lighter, empty, you won't really notice a weight difference above water, hauling just the tank. Below, you'll have about 6 or 7 lbs. negative buoyancy advantage with the steel (at @ 500psi), so figure on losing about 6lbs. off your belt (or integrated pockets), which actually gives a net loss of 4.5 lbs on your total rig above water!

And the upside just keeps on keepin' on...