Not an owner (yet), would like some advice...

[waterbear]

Blistering gelgoat can also be a water balance issue, not just a manufacturing issue. Some of the older gelcoat formulations were more prone to cobalt spotting and blisthering than current ones. It does happen (just like calcium nodules happen in plaster pools and wrinkles, bubbles, and fungus under the liner can happen in vinyl pools). It most likely means the pool was not properly cared for. My guess is that the original owners were using triclor tabs and never paid attention to pH and TA and the pH was very low for an extended period of time. Same scenerio will also damage a plaster or vinyl pool btw and is fairly common because many people only test chlorine (if that--as someone who worked in a pool store I know first hand how many owners care for their pools. Granted, it they are trying to keep from being "pool stored" but they thing that all they need to do is add chlorine and that everything else, inlcuding water testing, is just a reason for the store to sell them something.) I have also seen some information that osmotic pressure plays a part in blistering so keeping the calcium harndess up can be another safeguard (there are some who believe that calcium is not needed in a fiberglass pool same as in a vinyl pool but I have seen some reports indicating otherwise for fiberglass so let's leave it at that.)

Blistering can also be a manufacturing defect and there was a filberglass company that I won't mention (and it was not San Juan) that did have problems with their gelcoat, particularly their colored one (at that time they offered blue in addition to white). There are also some smaller fiberglass pool manufacturers that have come and gone over the years that had a lot of problems with blistering of their gelcoat. This is why I gave the warning about Trilogy. They just have not been in business long enough to see a long term track record. I am not saying that their pools are bad, just that we don't have al history on them as of yet to be able to know how well they stand up. As I said San Juan has been in business for over 50 years now and Viking about 35 (and Viking bought Blue Hawaiian in 2010 after they had been in business for about 25 years). If fiberglass pools inherently had prblems do you think these companies would have been around for as long as they have? Ad far as the Pool/Spa industry goes, these companies are practially dionaurs!

As for the lengths I gave for plaster finishes above, realize that they are averages. There will be pools that will last much longer and those that will fail after a very short time. MUCH depends on how well the owner manages the water chemistry AND on the makeup of the fill water and these variables play a major part in how long any pool surface will last. A big problem with plaster, IMHO, is that how new plaster is cared for during the first year (which the pool owner is likely inexperience in pool care,balancing the water, AND the fact that water is the most difficult to balance because of the curing plaster during this time) is important to the life of the finish.