I just to tested the pool water (not that I want to go swimming, I just don't want bacteria)
PH was normal, but Chlorine was low. I don't see anything around that looks like or says chlorine. I do have half a bottle of pool muriatic acid. What is that for?

Adjust the PH. Makes water more acidic.

So should I go get a couple bottles of chlorine? I know where he used to shop, I might be able to figure out how much he used by their records.

Oh wait, we have a duck with chlorine tabs in it, maybe it is just empty. I'll go check.:rolleyes:;)

See: How to Properly Maintain Swimming Pool Water Chemistry - wikiHow (http://www.wikihow.com/Properly-Maintain-Swimming-Pool-Water-Chemistry)

OK I added 2 more jumbo tablets to the duck. I'll check it later after it has circulated some.:)

I added 6 chlorine tablets yesterday .Woke up and pool was milky.Should I take the tablets out of the tube.10000 gallons in pool.Cement in ground.

Without knowing all the test results on your water, it is almost impossible to tell what you need to do. You need to know the following: Total Dissolved Solids, Calcium Hardness, Total Alkalinity, PH, Free Available and Combined Chlorine. If you have a pool supply store in your area take a bottle of water to them and they will test it for free. They can then tell you exactly what you need to add to your pool to re-balance the water.