Basically, they are giving you the run-around. Liquid chlorine and "shock" (powdered chlorine) both add chlorine to your pool. All the other stuff is, for now, wasted money. It probably will be later, too.

You are going to need
1) a better test kit. You can seek out your local Wally World (WalMart) and see if they have the HTH 5-way test kit that uses drops. Or you can see if you have a local Leslie's that has a kit that measures to at least 5ppm of chlorine. If you are really, really lucky, a local Leslie's may have something called a FAS-DPD chlorine test kit. It may be a single kit, just for chlorine, or part of another kit. Either way, it's the first best thing you need. You can also order a FAS-DPD full kit on-line. There's the PoolSolutions.com PS-234--that's sold by the sister site to this one and run by the guy who owns this forum. Ultimately, it's the best kit. But there are two other really good ones that are nearly as good and just as accurate you can get FAST! The first is the Taylor 2006 test kit. The second is from Leslie's on-line: The Chlorine FAS-DPD Service Test Kit. I can't tell you how much these cost, but figure $60 to $90. It'll be the BEST bargain you can ever buy for your pool.

2) Lots and lots and lots of chlorine. Bleach works best. Ordinary laundry bleach. Pool stores sell it as "Liquid Chlorine" or "Liquid Shock" but it's the same stuff. Sometimes the pool stores sell it at "12.5%" which is basically double strength. To be imprecise, one gallon of 12.5 adds about the same amount of chlorine as as 2 gallons of bleach. So if a gallon of 12.5 costs less than double 1 gallon of bleach, it's a good price. It's still the same stuff, just more concentrated. Chemically, it's called Sodium Hypochlorite solution.

3) Lots and lots of POPP--That's Pool Owner Patience and Persistence.

4) The realization you will need to completely replace and clean your filter medium when you are done. That means a new cartridge, or new sand, or a completely cleaned DE filter.

Read the stickied posts at the top of each topic. I wrote a few, so I don't have to write them again....