Low calcium levels, plasticizers in vinyl liners, leaching cobalt from fibergalss?

[waterbear]

Langelier SI was designed for closed systems, not open systems like pools. It has some merit as a general guide but when you consider that pools are also balanced using the Ryznar(once again, from my understanding, usually applied to boilers and such) and Hamilton indexes and what is balanced with a certain set of readings in one is sometimes not in another makes you realize that they are just guidelines after all. It is interesting that a pool that is in balance by Langlier's equation might show up as corrosive under Ryznar. Which is correct? It is intersting that in the Langelier index(SI=pH+TF+logCH=LogALK-constant) pH is the factor that has the MOST influence in changing the output with lower pH making the water more aggressive and higher pH making the water more scaling. pH is the only factor in the equation that is used directly, Alk and CH are both used as a log10 of the reading which means big changes in the reading will only create small changes in the outcome of the equation. Temperature is, from my understanding of the equation, the second most changeable factor in the outcome of the equation since the Temperature Factor is the second largest changing variable in the equation. My feeling is that these should be taken as general guides and not as gospel as they often are in the industry and in the pool stores. I don't have the answers on this one but would sure like to know. I am currently running my pool using the Hamilton index which balances the TOTAL (not calcium) hardness and total alkalinity and the pool is run at a higher pH and buffered usually with borates (Borax, Supreme, Optimizer, etc.). This one was developed by the pool/spa industry and from what I understand has about 10 years or so of empirical evidence to back it up.
PoolDoc has an interesting article on high pH pools on the Poolsolutions website.
http://www.poolsolutions.com/gd/hiphpool.html
Would love to hear his take on all this. I DO keep some calcium in my fiberglass pool becuase I fill with water with 0 ppm hardness and I do have grouted tilework and a marble spillover in my spa. I keep my calcium at around 150 ppm. I just hope I'm doing it right but I guess only time will tell!
mwsmith2, I have to say your logic does make sense to me. Don't know if you are right or wrong but I think we are basically on the same wavelength.
Since I have a SWG and my pool seems to like to stabilize at around 7.8 pH it seems like a high pH pool was the easy way to go for me (I've said many times before in this forum that I'm lazy!)