Pinecube
Contributor
Weight you carry on land is supported by your back. Weight you carry in water is supported by the bouyancy of your BCD and exposure protection. What might have changed is your trim. Different tanks will affect your trim differently. With the 15L tank you may have unknowingly been arching your back to compensate for the trim which can give you a sore back.
The instructors on this board could probably explain it better, but I found this out the hard way on a trip to the carribean. I was wearing rental gear and I didn't take the time to properly weight/trim myself. In my case the BCD was probably too loose as well and I ended up with a sore back later that evening.
The instructors on this board could probably explain it better, but I found this out the hard way on a trip to the carribean. I was wearing rental gear and I didn't take the time to properly weight/trim myself. In my case the BCD was probably too loose as well and I ended up with a sore back later that evening.