If you haven't put anything but the Super Shock and Swim in the pool, then you have no stabilizer (see why we don't trust strips). With a pool the size of yours, you might consider liquid stabilizer (also called conditioner, Cyanuric Acid). You'll probably need 1/2 a gallon to 3 quarts. It's more expensive than granular stabilizer but you won't need much.

I'd plan to run the filter all the time there's no one in your pool. The Intex cartridges filters I had when I had my 15' donut just don't seem to deliver water clarity.
I would not run the filter when someone is in the pool. I just don't trust the insulation on these pumps and there is no other means of electrical protection.

You can see if you can get the HTH 6-way kit Watermom mentioned here(Check Availability). "Guess Strips" are just not reliable enough.

It's really not hard once you get the hang of it; you're going to love your pool.