text: scuba ?: how many pounds of lead is needed for a person weighing 170 lbs? please answer asap, my scuba instructor is allowing us a bonus question (this is it) and we are allowed to get any help we can.  please don't answer unless you know what you are talking about! thanks... this is a starting guideline for salt water: for a 3mm wetsuit: body weight (170 lbs) x 10% = 17 lbs 80 cu ft aluminum tank: add 5 lbs = 22 lbs for fresh water @ 170 lbs, subtract 6 lbs = 16 lbs