A couple days of posting and getting your questions answered, and your nerves will subside.
What does the water look like? Green? Clear? Cloudy?
I'd return most of it if you can. Apparently we can't return pool chemicals, even if they are unopened, in Connecticut. Texas may be different. You'll hear a lot of recommendations for maximum strength liquid unscented bleach. You can get more concentrated liquid chlorine at the pool store or perhaps a discount store (We have Ocean State Job Lot in the Northeast that sells true 128 oz. gallons of 12.5% concentration Sodium Hypochlorite, which is the same active ingredient in household bleach).
Someone will be around to tell you about the tabs. They have CYA in them and will raise that level in your pool. The most efficient way to lower CYA is to do a partial drain/re-fill. but at 40 ppm you can probably get away with using them for a little while. Tabs aren't as much of an issue here but our season lasts about 4 month on the long side, we do partial drains every September in order to close the pool for the winter. In Texas, my guess is you can have a 12 month season if you tried, so tabs are probably bit less efficient.
Finally I've come to learn that "Shock" is a process, not a product (return it) and algaecide is misleading. Algaecide doesn't kill algae like the name implies. It prevents it. Chlorine does both. Chlorine at high concentrations kills algae. Chlorine at lower, sustained levels prevents it.
Strips are inconsistent at best, so the test kit is imperative. See Texas Splash's post above.
In any case, Welcome to the board!
