You're going to have to get a K2006 test kit, and monitor your CYA levels. For every 10 ppm of chlorine added, trichlor adds about 6 ppm of stabilizer. http://pool9.net/tk/

+ Keep your chlorine level at at least 10% of your CYA (stabilizer) level.

+ Trichlor also adds acid; use borax to keep the pH above 7.

+ Using bleach as a 'shock' will decrease the rate at which your CYA ppm rises.