If your pH is 8.0 and you have low cya, go ahead and use some of the pucks. As long as you monitor your cya and pH, you can use trichlor. In a 15,000 gallon pool, 2 lbs. stabilizer will only add about 20ppm cya. You have a little room to use pucks for a short time. How did you add the stabilizer? If you didn't add it to the filter, but instead have it in sock hanging in front of the jet --- remove the sock if you want to use pucks for awhile.