I am thinking that putting these in my skimmer with the hair net in place in the skimmer basket would act almost like a sock - I often only need a small top up of my CYA, so these might be more convenient for my needs...
I normally up my CYA in the spring, just after I allow our heavy winter rains to dilute our water (this helps me to keep CH in check). I also typically need to top up the CYA in the summer once or twice.
With our auto safety cover on our pool the vast majority of the time I only run the CYA at 30 and therefore just need small adjustments to bump it back into that range. Seems like one or 2 of these tabs would be something to try. I am almost out of the crappy slow dissolving Clorox CYA I have on hand, and this is the same cost as the other powder I was looking at getting, so I think I will give it a shot and report back.
Ok here is my take on this after adding 2lbs. The first pound dissolved with no problem in about 2-hours. The 3rd and 4th eight ounce water soluble container seemed to dissolve too quickly and seemed to clog the skimmer causing my pump to shut off. After breaking up the CYA the pumps turned back on. I also increased pump speed from 50 to 75 percent. It worked ok at first but I will probably put future doses in a sock to prevent the clogging. The good news is it does dissolve quickly. Pool math says I should add 2lbs more but I will probably wait and get a CYA measurement before I add more. Also, it’s winter so I’m not too concerned with the chlorine consumption rate. The chlorine level is at 2ppm this morning and I haven’t added chlorine in two days.
I just used a few of these to get my CYA back to normal for the upcoming swim season. My shipment arrived with a one or two of the "pods" broken, so I will use that extra powder in a sock when I need it.
I had similar results to Jbrillo - I have used 2 so far. The first one didn't dissolve particularly fast with my pump running at 1000 rpm. I had it in a skimmer sock in my skimmer basket. Once I turned up the speed to 2000 rpm it dissolved in less than an hour. I then put the second one in and it was gone when I checked back a few hours later. So they do dissolve much faster than the Clorox CYA powder I have used in the past - I think the crystals are smaller.
The real question is are they useful? I think they offer minor benefit of being pre-measured and quick to add and dissolve, which does make them a little more convenient than measuring and adding powder to a sock. Toss it in a skimmer (with a hairnet acting as the sock) and you are done.
I can have my 9 year old do the job for me when I am too lazy! "Head. CYA. Now." (cue Mike Myers as his Father in So I Married an Axe Murderer)