Yep, that's why we usually recommend the sock method.
One thing to consider is, that CYA is sold in Australia as a fine powder rather than the granules common in the US. As soon as this powder gets wet, it tends to clump together and these clumps become as hard as brick and take ages to dissolve.
I usually fill the powder into a sock and tie it to the end of a stick. While lowering into the water, I immediately start kneading the sock, that prevents the powder from turning into a brick. Then I either hang it in front of a return until the sock is empty. Or I just walk around the pool, pulling the sock on the stick through the water. Like that the powder leaves the sock pretty quickly and gets distributed uniformly around the pool. Some settles on the floor, which disappears quickly with brushing. I'll keep the pump running on high (only skimming, no cleaner running). After a few hours, the CYA usually registered as expected in the test.
