The HTH 3-in-1 Chlorinating Skimmer tablets are just calcium hypochlorite diluted with magnesium sulfphate. They've also added 1% sodium tripolyphosphate, which is a detergent of sorts. I wouldn't recommend them, but they are OK to use for now. HTH sells a bunch of different blends of chemicals under the term "shock", so I don't know about that.

Do this:

1. Get a cheap OTO / phenol red DROPS kit (yellow / red drops), and use it.

2. Get 10 gallons of PLAIN 8.25% bleach. Start adding 1/2 gallon each evening. Test chlorine before adding. If chlorine levels are light yellow or below, add a repeat dose.

3. Post the EXACT name of the shock material, so we can look it up, and see if you can use it.

4. READ the SS recipe page -- it covers many things you need to know.

5. You can continue to use the HTH tablets. Just don't pour the bleach on top of the tablets.