Need help with decision about purchasing two tanks...

[SWAMPY459]

My roommate and I dive together. We usually rent four aluminum 80's and dive two tanks each in a day.

I have an opportunity to get, for about the same price, either four aluminum 80 tanks or two steel 120's.

The aluminum ones would ensure that we always have two tanks each available, but that's also four vips each year and four hydros in five years...

The 120's would be one tank each (and we could always rent extra tanks if we need them) and only two vips each year and two hydros in five years...

I've read that steel is better for buoyancy also... but I've never dove with steel..

One article says that both can corrode, but properly cared for, they should last 40 years or more. What is proper care for a steel tank compared to aluminum?

Which would you do?

 

[Pedro Burrito]

I don't think I would ever buy an aluminum 80, you can rent aluminum 80's anywhere.

Most dive shops will fill any age steel in hydro and VIP but many will not fill a 26 year old aluminum, even if it's not 6351-T6 alloy and even if it's in VIP with eddy and hydro.

I've got two 40 + year old 72's and two new 130's. The 130's are like carrying a truck on your back but I don't have to carry much lead, even when diving dry. The steel cylinders do take some time to get used to. The first time I took my BCD with 130 off to practice doing laps with it in front of me, I did a nose dive and almost hit the bottom of the pool. I really struggled putting the BCD back on without touching the bottom.

You're correct, the cost of VIP's, hydros and O² cleaning does add up over time.

 

[AfterDark]

I like steel because it allows me to wear less weight. In cold water with a 7mm wetsuit steel is the way to go. In FL AL should be fine.If I were you I'd try diving a few steel tanks if you can. Steel 120's are pretty heavy compared to AL 80's, you don't want to find out after you buy them that they are too heavy and make you negative without weights! I've got 2 LP90's when I use them as ID's I don't wear weights. I carry a lift bag in case my BCD fails, when I use the 90's together. Steel tanks are very durable. All my steel tanks are at least 20 years old. Proper care? Don't breathe them down to empty that could allow water to get in the tank. Galvanized is better than paint. Store them standing up if water does get inside all the rust will be on the bottom and easier to remove. Make sure the hydro and vip are current if not ask the seller to get it done or agree to finalizing the sale only after the tanks pass. Good luck

 

[Bob DBF]

Depends on how much diving you do and the availability of air fills between dives.

I picked up 2 AL's for my first tanks in NorCal because I wanted to be able to make two dives without having to go find an air fill, which were few and far between, not counting the hassle of getting the gear off and packed to go get the fill. I've added steel tanks since. It was a pita to use AL tanks in cold water, but was offset by making the two dives instead of one.

Since Fla has dive shops every few feet, renting a tank would not be the hassle it still would be for me even today, If I were you I'd get the steel tank and start saving for the second, you will be spoiled by the steel 120.

With any tank, don't get water on the inside, and rinse the saltwater off the outside, and handle them carefully so they don't get too beat up.

Oh, by the way, if you think viz and hydros are expensive, you picked the wrong hobbie.



Bob
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I may be old, but I’m not dead yet.

 

[EasyDayDiveCharters]

Swampy,
I personally dive steel tanks and honestly don’t rememberthat last time I’ve used Aluminum tanks. Like others have mentioned, you are able to ditch some lead when divingwith a steel tank.
Aluminum tanks will work just fine, but like Pedro said, youcan rent AL anywhere without any problems. Rental steel tanks, from my experience are a little harder to comeby.
Maintenance will be cheaper for two tanks compared to 4, butsteel tanks cost a little more to hydro, compared to AL. The difference here in PCB is $30 for AL and$40 for Steel tanks.
Care will pretty much be the same between the two. I always hose off my tanks after diving andnever let it drain completelyJ. You will do VIPS every year and Hydro’s every5, so maintenance wise they are the same.
I would personally go with the steel tanks myself. Those are 120s, which are some pretty bigtanks and if needed, just rent one AL.
Cheers,
-Capt. Brandon

 

[Linedog]

If you buy the steels, and then rent Al, it will be a pain to swap weighting between the two for a two tank dive, one steel and one Al.

 

[Steve_C]

Its not just steel and aluminum. The tanks are different sizes. I have a pair of AL80s that I still use on rare events or to lend. I dove a number of different tanks and settled on Steel HP 100s as my regular tanks when using my own. I found the 120s a bit too big. I liked the fact that the 100s were shorter. The 100s fit perfectly on my short frame. The AL80s and bigger steels are a tad long.

 

[CT-Rich]

I have a steel 100 and two steel 72s. I was annoyed when I borrowed some AL 80s at how bouyant I became at the end of the dive. Steel has better trim characteristics and as was pointed out requires less lead. I recently picked up 3 AL 80 tanks for an acceptable price (free). going to sell off one of the to cover the cost of inspections and will tollerate them until I can get another steel 100. The down side of switching between Steel and AL tanks is that you are going to have pay more attention to weights. When going between my steel tanks I just adjust the strap and leave everything else the same. Using both, you will have to add and remove weight when changing tanks.

 

[lv2dive]

Are they LP or HP 120's? The characteristics are different, and depending on the brand the lengths and diameters can be quite different.

If they are LP Steel 120's - and you are getting overfills (which I assume you will, given your location) - you will have approximately the same amount of gas in a single tank that you have two AL80's. Regarding the need to swim it up - personally, I can hold a stop with double steel 95's with 500 PSI so I imagine you won't have a problem with 120's but you should test it out to be sure.

I'd go for the steel tanks personally even though they are usually awfully long. Here is a link to one of my favorite my reference pages: Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan

 

[rsingler]

Are they LP or HP 120's? The characteristics are different, and depending on the brand the lengths and diameters can be quite different.

I'd go for the steel tanks personally even though they are usually awfully long. Here is a link to one of my favorite my reference pages: Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan

Wow! GREAT comment! Didn't realize the weight difference between "same size" steels from different manufacturers and/or LP/HP.
I'd figured an LP would generally be lighter due to thinner walls, but I didn't account for the size difference to get the same CF.
An example:
PST 120 HP holds 3550psi and 122.5CF at 39lb empty.
PST 120 LP holds 2640 (@+10%) and 122.5CF at _51lb_ empty!!
even a Faber 120 HP holds 3563 (@+10%) and 120 CF, but 48lb!!, so the manufacturer/alloy counts too!
At least according to the chart above.
I'd save for the lighter tank/stronger alloy. Your back will thank you on a week's trip.

If they are LP Steel 120's - and you are getting overfills - you will have approximately the same amount of gas in a single tank that you have two AL80's.

My math says 77 CF x 2 = 154. Yeah, 122.5 CF is almost the same.
While I agree with steel vs AL, maybe just a little exaggeration.
Now I'm going to sell my Faber 95 and 71 for some HP steel. New VIS/hydro 2/13. Anybody want a real steal/steel?