I've added CYA into a T-shirt in the skimmer and kept the pump running and it dissolves within a day and measures nearly fully the next day. This is for fairly small additions of 10-20 ppm. For larger additions I would expect having to refill the skimmer T-shirt about twice a day for a couple of days. Note that if you use this technique, you must have alternate suction flow so that you don't block the skimmer and break it. I not only have two floor drains in addition to the skimmer, but the skimmer also has a port below it that sucks in water if the skimmer gets clogged.