redundant

This wing is pretty much like new. It is the OMS Trieste 60lb version (redundant bladders). I got it as a part of a complete BP/W setup I bought used but haven't moved on to doubles so am still on a mono wing. I figure its better to get it to someone who will use it! The prior owner supposedly...

I'm currently looking into a Redundant Air Supply for recreational diving, and the only thing I'm unsure about is what size of tank to get. I've researched this enough to know to stick to 19cu or above. For Context: Most of my ~35 dives are solo, and around 30-60ft. I'm comfortable at 100ft...