I've seen reports of this parasite over the years but it was on ABC News again last night so I did some research and found this very interesting thread where chem geek gives a pretty good explanation of the situation you would be faced with if you had some of the CYA levels recommended on this forum.
Response to Cryptosporidium Post
I've looked around on the web and can't find a test. I think it is hard even for a doctor to find a lab that can test fecal matter in a patient for it. I know this mainly pertains to public pools and I'm not trying to be an alarmist but since the post cited above was in 2008, I was wondering if anyone had anything to add. It seems to me if you had CYA levels of 30 or 60 to 80 ppm you would basically be up the creek. Is that right? Of course you could spend $$$ on ozone and ultraviolet lights or drain your pool. This is all worst case scenario of course. I guess it eventually dies after about 10 days under normal or higher than normal chlorine conditions but I don't know. One thing I do know is that no one at my house takes a shower before getting in the pool.