Should I buy a tank, or wait? If buy, What would be my best option?

[Nitrox_DiverNY]

I agree with several people above who suggested/implied that you should wait, chat with and learn from the people who routinely dive the location(s) you will be diving, and learn your best gear (including tank) options from those people.

rx7diver

I think that's the best option too, thank you for the help!

 

[OTF]

If you're going to dive local (or drive to most of your dive sites) buy tanks! Rentals add up fast, and a lot of shops charge for keeping the tanks multiple days which is often unavoidable. Tanks last a very long time and hold value decently well compared to other gear. There's something that simply feels nice about owning your own full set of gear and being able to go diving anywhere on short notice. But yeah do the research, talk to people, and look for deals on used stuff before buying.

 

[CT-Rich]

Yes, but I am going to assume that your response indicates that as a new diver you don't understand the difference between PSI and volume. A cylinder has the advertised volume of air in it only when it is filled to its rated capacity. Fill it to different pressures and you get different volumes. To give you an illustration, let's see what happens if I fill 4 different cylinders to 3,000 PSI.

1. An AL 80 filled to 3,000 PSI will have about 77 cubic feet in it. (We think of it as 80, but it is less.)
2. An HP 100 filled to 3,000 PSI will have roughly 80 cubic feet in it.
3. An LP 85 filled to 3,000 wil have roughly 100 cubic feet in it.
4. An LP 108 filled to 3,000 will have roughly 120 cubic feet in it.

3 & 4 are filling tanks over their rated pressures and generally something that won’t happen. Being on Long Island, used steel tanks should be available. Do your home work and spend time learning what you need to know about tank types and how they hold up over time. Steel is expensive new, but you will never need or want to replace the right choice. Aluminum tanks have some draw backs (and life expectancy issues with older tanks). But, they may do what you are looking for them to do, especially if you have a very low SAC (air consumption).

when buying used, it is important to understand what additional expenses you may have buying something from a stranger. Tanks out of hydro may cost $50 to have them tested. Some shops will not fill old Aluminum tanks (right or wrong). Your off the rack BCD may have to be adjusted for different sizes of tanks. You may want to buy tanks that have same diameter, so you don’t have to adjust cam bands when swapping tanks.

For example, my HP Steel 120s are the same diameter as my daughter’s AL 80s. I am an air hog at 6’7”, 240 lbs. she is 5’9’ and 140 lbs. I can handle big tank and make use of the extra air. She would have trouble with a big tank and will last just as long as I will with an 80.

 

[boulderjohn]

3 & 4 are filling tanks over their rated pressures and generally something that won’t happen.

My purpose in the post was to explain the relationship of PSI to volume, which the OP did not understand.

BTW, diving in south Florida, my LP tanks are routinely filled beyond 3,000 PSI. Diving in North Florida, they are routinely filled beyond 3,500 PSI.

 

[Jim Lapenta]

I have started getting rid of some of my cylinders. I had 5 al80s and now have one. Two I sold and two are now at the shop I work with for rentals because I just don't dive them. The 80 I keep is stage cylinder. All of the cylinders I use regularly are low pressure because I know I can always get full fills. Some local places just don't fill to 3442 cool.
We will, but you're going to leave it overnight to get that full fill.
LP cylinders often see 3000. Even at busy places. They are so used to dumping 3200 in hot to an al80 so it will cool to 2800-3000. Fine with me on my steel tanks.
Steels also last longer and while more expensive upfront, in the long term they pay off. Many shops won't fill older al80s (pre 1989) because of issues with the 6351 alloy used. Doesn't matter if it wasn't of that alloy, they just have a policy of no older aluminums.
I have no issues getting my some of my 40 and now (60 year old) steels filled.
Someone else has also mentioned to not just buy one cylinder and I also recommend this. Unless you know you will only do one dive, get a pair and that way you won't have to run for fills after every dive.
Do you own a car? I have some customers in NYC who don't. So if they have cylinders or rent them, they need to bum rides, take them on the subway, or rent a car to dive.
Don't just buy a cylinder because someone says "get a HP100 because I like them." Dumbest reason to buy one.
You need to know what your needs are the first step in that is knowing your SAC rate and RMV -how much air do you use.
So determine your SAC rate and covert to volume - RMV.
Then do the gas calcs for the dives you want to do. For that you'll need to know your cylinder capacity. How many cu ft of gas do you use?
What if you can't get HP fills? HP tank is then a waste of money.
Cylinder content at a given pressure is determined by diving the rated capacity by the working pressure.
Ie LP95 is 95 / 2640 (2400 = 10%) = .036. You get that filled to 3000 psi and you have (3000 x .036) 108 cu ft of gas to work with.
Take an RMV of oh .46 for a dive say to 99 ft (4ATA x .46) and in theory you'll use 1.84 cu ft per minute. 20 minute dive you'll use roughly 37 cu ft of gas. LP95 is fine
What is enough for you? Remembering that you may also have to assist a buddy who goes OOA.
Then everything changes.
Now your SAC may double and you have a muppet who ran out of gas with double his normal SAC (possibly triple).
That 95 may now be just enough.
I have an entire chapter on gas calculations, cylinder matching, and even tables for popular cylinder capacity at different pressures in my second book. There are also other resources to calculate gas needs.
This is why it makes zero sense to make a blanket recommendation on cylinder size. They are not cheap. It's an investment you need to make with care as to capacity, composition, maintenance, storage, fill options, etc.

 

[Jim Lapenta]

My purpose in the post was to explain the relationship of PSI to volume, which the OP did not understand.

BTW, diving in south Florida, my LP tanks are routinely filled beyond 3,000 PSI. Diving in North Florida, they are routinely filled beyond 3,500 PSI.

Not just Florida. Dive the Great Lakes and Midwest deep sites? 3000 - 3300 in LP steels is not uncommon.

 

[Belzelbub]

renting vs buying tanks will depend on dive frequency, maybe rent a few times to dive long island/NJ to decide if it will be something you do somewhat frequently. of course, if some good and cheap steel tanks are posted on fb marketplace/craigslist, that may simplify the decision too.

I agree with that for the most part, but would add that owning tanks also allows for greater flexibility. Most of my dives are from a boat. My own boat, usually. In most instances I may plan to go diving a few days in advance, and there is always a caveat of weather permitting. In several instances, I’ve had to cancel the night before, or morning of. Since I have my own tanks, it’s not a big deal to just push it out to the following weekend.

Renting adds some complications.

 

[MikadoWu]

hello all... Im trying to decide if I should buy a cylinder or not, but if so doing a bit of looking to see what kind of cylinder would be the smartest option for me to buy. I just got open water cert but already have scheduled AOW, Nitrox and plan on being quite an active diver. I am even considering a career change to the diving world. Im hooked. Im in Florida a few times a year to visit family and that is where I got my OW and will be getting AOW, Nitrox, but I live on Long Island New York. After I get my AOW this month I want to look into diving the northeast. Ny, Nj, Maine, and NC. At this point is it worth it to buy a cylinder after my AOW for diving the northeast or should I just rent? I have all the other gear including a BCD, Hog D3 regulator, spg, wetsuit, fins, boots, computer. I like the idea of having my own gear for my own "perceived" safety compared to renting it, if that makes any sense. Would steel make more sense for "colder" water diving since it is more negatively buoyant? What size cylinder is most widely used on the east coast for say a 100ft dive to a wreck? Thanks for the help!,- Will

I know I am a little bit late to the game, and it does not answer your question, but do you own all the rest of the Gear? If you plan on Diving up North, Drysuit, Computer, BP/W and Regulator are priority. Many shops do not rent Drysuits. Once you have all this, you can dive the different Tanks and see what performs for you. Steel, most likely, but what size will trim you out best.

 

[Cio]

good to know, I will have to do some more research into the pros and cons of both. But even if you could not fill the HP up to capacity you could still have it filled to 3000psi right?

You are in NY, everyone dives HPs, fills wont be an issue.

 

[formernuke]

4

I over bought, I have a lot more than 4 steel tanks.

OP as stated most of us cold water divers use steel tanks. Exact size depends on your body.

If you dive a lot owning your own is worth it if only a occasion diver its cheaper to rent.