Spishex - thanks for the link to Richard's detailed post on zeolite and the explanation why it's not all that great for dealing with ammonia. I certainly see the logic -- and in fact it's not really my main concern, it was high calcium hardness. I figure the first step, though, is to find out whether the salt in a SWG pool renders it ineffective, and it seems it's much better known for its alleged ammonia skills and less for its alleged calcium cleansing properties, so I led with phrasing it as an ammonia question. You guys obviously didn't need to be treated so carefully, the responses here are remarkable. I think Richard is exactly right as to the ammonia issue.
Waterbear - Great post on sand and DE. If it was really cleaner water I wanted, I'd go with your solution. My water looks terrific, though, so I don't know if I'd notice the difference with a more effective filter. The tips on cleaning a sand filter annually sound like a great idea - mine is 2 years old and I think I'll give it a try.
Duraleigh - thanks for the welcome. You identified my real goal here: find a way to get rid of calcium, other than draining. My house has no municipal water supply, and my pool fill comes from a well filled with water from the Biscayne Aquifer under Miami, an aquifer imbedded in calcium-laden coral rock. CH in my pool is 500, and I suspect it's the reason why my skin feels "squeaky clean" - that is, the polar opposite of silky - and irritatingly sticky to the point of sharp twinges of pain sometimes. Draining my pool is no help -- the fill is just as laden with calcium. Here's the link that got me thinking Zeo-xxxx would help:
http://www.poolwizard.net/problems/hardness.htm. To quote from the bottom of that page:
"Zeolites, and clinoptilolite in particular, reduce pool water hardness when used as a filter medium in sand filters. They achieve this by ion exchange and adsorption of the calcium molecules. Regeneration with salt flushes the calcium out of the zeolite and it can then continue to remove excess calcium."
I've really got two questions: (1) does whatever effect Zeo-xxxx may have get nullified by the fact it is being washed over constantly by salt in a SWG pool; and (2), if not, and SWG salt levels do not reduce its effectiveness, does Zeo-xxx do what that website claimed -- reducing calcium hardness?
Thanks