Each pound of trichlor or dichlor used will add approximately 1/2 pound of CYA to your pool, considered from the point of view of bulk chemical.

As active percentages, dichlor is 55% available chlorine and 50% CYA; trichlor is 90% available chlorine and 60% CYA. (I know those don't add to 100% -- it has to do with the way "available chlorine" and ppm chlorine in water is defined.)

As ppm FC added to your pool, for each 1 ppm of FC, trichlor will add 0.6 ppm of CYA; dichlor will add 0.9 ppm of CYA