It is ok to use cal-hypo for awhile but it does cause the calcium hardness reading to increase. If it gets too high, it can cause cloudy water issues.

You really need to get a kit so you don't have to rely on the pool store for testing. The one we recommend is the Taylor K-2006 or 2006C (same kit, larger bottle of some reagents). If you buy it through the Amazon link in my signature, the Pool Forum makes a little money on the sale which helps us keep this form online. Only buy if the seller is Amato Industries, however. Some other sellers are substituting the K-2005 which you do NOT want. If Amato isn't listed, wait a day or two and try again. They seem to restock pretty quickly when they sell out.

At the very least, pick up the 6-way test kit at Walmart.