What size cylinder should I buy?

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Baltimore, MD
# of dives
200 - 499
Working in pools with students, I use my wife's gear. A Seaquest Libra (back inflate BC) and either my LP77 or HP100. With a 3mm wetsuit, I don't need any lead. My buddy and Instructor I work with uses his HP80. Again, no lead and a 3mm wetsuit.

When it comes to salt water, I switch to my normal rig, which is a hog harness and SS backplate. With a 3mm suit and my HP100 I'm a couple of pounds negative at the end of the dive, but nothing I couldn't swim, and I carry a reel and SMB.

I wouldn't get too wrapped around the axle over ditch-able weight if you're close to neutral at the end of your dive.

I'd give another vote for the HP100's or HP80's.


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Texas, but about to move to waterless Shreveport f
# of dives
100 - 199
Are you sure you want to get rid of all your ditchable weight?

The very first thing a rescuer wants to do is get a victim positive at the surface. Maybe the BC works, maybe it doesn't. But ditching weight is always a step in the right direction.

If the incident occurs at the beginning of the dive when an HP 100 is 10.5# negative and the wing is blown, there might not be a way to get the diver positive other than ditching the entire rig. This then removes one tow method from the list of possibilities. It also means there are less options for providing air to the diver because their rig just sank to the bottom of the ocean. Of course, there is the time lost trying to figure out why the diver keeps sinking...

In a way, cold water divers (wetsuit) have it made. We always need a lot of weight so we can put some on cambands or use heavy backplates and still have several pounds of ditchable weight. Steel tanks are ideal for cold water divers.

Warm water divers have it made, too! I LIKE warm water diving. But I like it better with a less negative tank and perhaps 4-6# of ditchable lead. If I were diving in warm water again, I would be using an Al 80 but I would consider a steel LP 72. I think I would be looking at tanks that are definitely positive at the end of the dive to ensure that I needed some ditchable weight.

Just something to consider...


Yes, I have considered it and the issue has been discussed here on SB as well as with my dive buddies. It seems just silly to ADD more weight for the sole purpose of IF I ever need to ditch it if I'm perfectly neutral and trim and can hold my position in the water at 10ft. Any weight I put in a ditchable location will make my trim go out of wack. Therefore, the solution for me at this time and in this configuration is to put the 4lbs in the trim pocket which keeps me trim and neutral regardless if I'm at the beginning of the dive or the end. My dive buddies know that I don't have ditchable weight and are okay with it. I just figure if I can't swim my 4lbs in lead up at any point in the dive without having to ditch (or remove my BC) then I've got bigger issues to deal with. Thanks for your concern, though. It's nice that divers are always looking out for one another, regardless if they are strangers or not.
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New York - Hudson Valley
# of dives
200 - 499
LP is typically a pressure of 2400, and if a "+" rated tank, you can add overfill by 10%, for a total of 2640psi. I have heard the 10% overfill rating no longer applies once the tank goes for hydrostatic testing.

HP is 3442 PSI, and while there are Yoke regulators rated to 4000 PSI, most are not. You'll need to see what is physically cast or stamped into your regulator yoke. A conversion to DIN is generally recommended for HP connections such as this.

Concerning size, you might find the 100CF HP is a nice trade off of capacity and size, and while you've seen comments that you can't change the amount of weight you wear, the buoyancy fact is the steel tank will be 5-6# negative while an empty aluminum is 3-4# positive. I always leave the extra 5 I put on for an aluminum off my belt when diving a steel....


I've decided to check out the HP80. I'm hoping I can borrow a buddies cylinder first to make sure it will work for me before purchasing. Thanks for all of your helpful suggestions!

I suggest you also look at one of these: LP 85 Steel Tank reviews and discounts, XS Scuba

You are in TX so you should be thinking about gear for the Flower Gardens. You are good on gas so an HP 80 might be fine but the Fling will probably not be able to get you to 3442 psi. You'll probably have to do with 3100 to 3200 psi which may be a bit tighter than you want for those dives. My favorite tank is an HP 100 but that is probably more than you need. The will probably leave your LP 85 around 2700 to 2800 psi which would be fine for you out there. Plus its buoyancy characteristics and size/weight should suit you just fine.

Or you could just go with the HP 100 and never have to worry much about having enough gas. And it is almost the same as the LP 85 from a size/weight standpoint. Just a bit tougher on the CC.

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