Denise:

With a high CYA (Stabilizer) you have ONLY 2 options:

1) Run a high CYA/High Chlorine pool. That means your Free Chlorine (FC) has to be between 8 and 15 for daily use, and you shock it to 25 ppm when necessary. You need a proper test kit for that.

2) Dilution. If you drain half of your water off and refill, you'll STILL have a CYA of 50--the high end of the recommended level, but easy to manage.

Those are your choices. If someone tells you there's an additive to remove CYA, don't buy it. It will cause you more trouble than it cures and you'll WISH you had drained and refilled.

But then there's the problem of your excessively high calcium (CA) as well. It's in the 500's--400ppm is the max for a concrete/gunite/tile pool, or a pool with an SWG or heater. 500 is the absolute max for a vinyl pool without those things. If your Total Alkalinity creeps up just a tad above the 80-125 range, your water may go suddenly cloudy on you.

To make this worse, your Total Alk is low and needs to be raised to the 80-125 range or your pH will bounce around on you (see how everything is connected?) My suggestion is to raise Total Alk to 100ppm, no higher and never use Soda Ash to raise pH (if you need to do so), but only use Borax for that.

Draining off half your water and refilling would again be the solution, but ONLY if your fill water isn't high in calcium--you should test it.

If you elect to run a high CYA/High Chlorine pool, you need to get a FAS-DPD Chlorine test kit. You can get Ben's kit, a Taylor 2006 kit, or Leslie's Chlorine FAS-DPD Service Test Kit (only on-line--it's the Leslie's branded version of the 2006, but it's the same kit I believe).

Or, both Taylor and Leslie's offer on-line a test kit that is JUST FAS-DPD for chlorine.

But if you do so, with your water, you need to:
a) Keep FC in the 8 to 15 range and CC <.5 to keep your water sanitary
b) Keep your Tot Alk around 100, so you can keep pH from bouncing around, but not so high that the calcium comes out of the water in clouds...
c) Don't let your pH go too high--I'd guesstimate 7.6 MAX. As pH rises and falls, Tot Alk moves with it--so if it goes too high....see b)!
d) Do NOT use tri-chlor pucks (adds CYA, low pH), di-chlor powder (adds CYA, low pH) or cal-hypo (powder or tablets--adds calcium) to chlorinate. At this time all 3 are super-trouble for you--only use bleach or liquid chlorine to chlorinate. I repeat ONLY bleach or liquid chlorine!
e) Stay away from ALL pool store additives. You CAN keep your water clear, sanitary and sweet with your numbers, but not if you start throwing in the (expensive) garbage they will undoubtedly recommend.

Test, test, test!