spearfisher

Steel all the way. No doubt about it. I've dove with just about every tank I can think of from big to small, aluminum to steel, high pressure to low pressure, and what works for me is an LP (low pressure: 2400psi) steel 95 or 108. I have a pair of both, and depending on what dive I'm doing I'll use either. I usually keep a richer mix (36%) in my 95's for shallower dives, and a leaner mix (30%) in my 108's for deeper dives. The major benefits of steel are the ability to overfill, and the bouyancy characterisitics. I wear a back plate, wing, and harness BC, and with a steel 95 or 108 I don't have to wear any weight with up to a 7mm wetsuit. It gives me PLENTY of gas to do anything I want (my last dive on the Oriskany yesterday was to a max depth of 130ft, and my bottom time was 67 minutes.) Aluminum tanks become positively buoyant at the end of a dive (the bigger the tank the more positively buoyant they become) and you have to overweight yourselfat the beginning of a dive so that you are not floating away at the end of the dive. I don't like that characteristic of aluminum tanks. The 2 major draw backs to steel are 1.) cost and 2.) the potential for rust. The cost is about 1.5 to 2 times more than an aluminum tank (but well worth it in my opinion.) As far as rust goes, get a galvanized exterior finish on the tank and it will last forever. The interior is a different story. If you get water into the interior of a steel bottle and leave it there, you can throw the bottle away. That's pretty easy to prevent though as long as you don't run out of air while under water (which will be pretty difficult to do with 108 cubic ft +).So in my opinion, the benefits far outway the cost. If you are going to buy tanks buy steel. If you are thinking about buying aluminum, keep renting until you can afford steel. Just my opinion.