As a diver that has more than 500 dives on steel 130’s heres a few tips I can pass along... FIRST OFF..you will loose some of that 28lbs but only you can tell how much by getting in the water with them and do a check of your own. Remember one thing , the weight difference with a full and almost empty tank are very different. you may want to do a bouyancy check at about 1300psi for a high pressure and 800psi for a low pressure(in a pool or very close to shore for these tests is safest)...SECOND..The tanks weight alot more than an aluminun tank so be careful with lifting and it takes more energy to get around on a rocking boat with a steel strapped on.... all in all I love the extra air and after a bunch of dives you wont want aluminum 80’s unless you need stage botles... hope it helps... by the way I now dive 130 steel doubles and love them... 3 dives a day and still air left... i usually get cold before I run out of air...lol.....STAY SAFE