Using Tri-Chlor to start season

[SunnyOptimism]

In a 10,000 gallon pool, each 3" tri-chlor puck (~8 oz) will have the following effect on your water assuming your TA is within normal ranges and assuming they are 99% tri-chlor (have you checked the ingredients?):

Raise FC by 5.5ppm
Raise CYA by 3.3ppm
Lower pH by 0.29ppm
Raise Salt by 4.5ppm

The above assumes a fast dissolution rate which, as you can see, does not happen. A better way to start your pool would be to raise your CYA to the lowest value you want in a season (example would be 30ppm) using powdered stabilizer and shock-clean your pool assuming you are at your target CYA level. You can then use the pucks for chlorination until your CYA maxes out to 50ppm (would only take about 6-10 pucks to max out).

Save the bucket of tablets for vacation time and when you have to ignore your pool for a few days. They will last a long time if you keep them in a tightly sealed bucket in a cool dry place.