A couple issues to be concerned with:
- Did you add stabilizer? That's critical. You want at least 30 ppm CYA to go with that FC to protect the pool and swimmers, and well as protect the FC from the sun. The sun will eat that chlorine quickly with no stabilizer (CYA).
- With pump running, you can test or add more chemicals about every 15 minutes
- Test strip ... no good. You MUST have the proper test kit, and by that I mean TF-100 or Taylor K-2006. Get that now while your pool is new and algae-free. Best simple investment you could possibly make for your pool.
- Also watch the pH. You want it in the mid 7s.
Checkout the Pool School page (link below) for more info. Hope that helps.