Starting the conversion... and have questions.

[CarlD]

I just opened the pool today,(15x30 above ground) and topped it off with water. I started the conversion with 2.5 gallons of bleach. I know I need more, but don't want to over do it.

The pool turned a greenish/yellow which is what I expected. So far so good, but now some questions.

1. I'm using a Taylor FAS-DPD testing kit. I'm no chemist, so the manual is kinda confusing. Do I need to dilute my sample with distilled water using this kit?

No. It's easier than it reads.
a) Get your water sample (usually 10ml)
b) Add 1 scoop of FAS-DPD powder and swirl. If it turns good and pink or reddish, that's enough. Adding more does nothing. If it doesn't turn, add another scoop. If it STILL doesn't turn, you have no chlorine.
c) Add one drop of the reagent (in a Taylor kit it's K-0871) and swirl. Keep doing this, COUNTING THE DROPS, until it goes clear. If it has a slightly pink hue, add another drop.
d) You are measuring FC. Each drop you added indicates .5 ppm of FC. So 5 drops means 2.5ppm of FC. FC is Free Chlorine the good stuff.

e) Now measure for CC (Combined Chlorine or Chloramines)--indicator of fighting something. CC is what gives pools that "chlorine" smell...you get rid of it by adding MORE chlorine.
f) Add 5 drops of the DPD Reagent #3 (R-0003) and swirl. If it stays clear, you have no CC. If it goes pink-tinted or pink you have CC.
g) Again, just like above, add the reagent R-0871 (in the brown bottle) until it goes clear. Again, each drop is .5 ppm, but this time of CC.

h) Add FC and CC together to get TC--Total Chlorine.

2. I'm assuming the chlorine level that is to be held at 15ppm is the Combined Chlorine? or is it the Free Chlorine? or the total of the two?

See above--it's FC you are aiming at.

I just tested and my Free Chlorine is: 1.5 ppm and Combined Chlorine is 7.5 ppm. I'm going to add another gallon for the night.

Thanks for any help.

I'm guessing you have around 10,000 gallons of water. One gallon of bleach will add 5.25ppm of FC to that (a little less if you have more water). So... you should add 3 gallons and aim to keep FC at 15ppm until the CC goes to zero. (0.5 is OK--it means you have some CC, but .5 is the MOST you can have--it's sometimes tough to get below that).

BTW, you only dilute if you are using an OTO test for Total Chlorine--do NOT dilute the FAS-DPD test. It measures up to 50 or 100ppm. FYI, when you dilute, it works best if your OTO kit measures to 5ppm, not 3ppm as many do--you have to dilute too much to get even a vaguely accurate reading.