If the test doesn't go red, then it usually means there is no calcium hardness. That is possible--I don't have any calcium in my fill water, either. If you don't have a heater, then it will be okay--vinyl lined pools don't need calcium to keep the water from leaching from the concrete, because there is no contact.
Ben has commented on past occasions that in some liners, there may be components of the liner that can weaken without the calcium, but when I started my pool up and asked the same questions 5 years ago, his comment was that as long as I had greater than 20 ppm or so, it would be fine. 5 years later, my liner still looks new, so I trust his judgement.
So...if you find a good deal on cal-hypo, I would just use that to chlorinate with for awhile, until your calcium gets up to 200 or so, then switch to plain bleach, and that would kill two birds with one stone!
Janet
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