Not that it matters but I am curios what brand it is, this information will also help us to direct you on your options. Sometimes a blister is minor thing, other times they just keep showing up. Depends on the manufacturer and there record. Alot has to do with the process, some manufacturers have a process that cuts corners and seperation of acrylic and fiberglass is more likely.
Thanks for the feed back the spa is a demension one. It is there @ Home series which I believe is their base line. I would think it would hold up at least 1 year, but maybe the contract out for this series.