I have heard they don't dissolve in the water first off, so you have to just pop them. So basically what your left with is a product something like Seachem Stability, except injected into little a little gel capsule, and priced over triple the amount!
I use them. I bought them after suffering an attack of cloudy water straight after starting my tank.
I put one or two in the tank itself and it dissolves and stick one or two into the filter.It's an expensive pot but the pot lasts a while - I put them in post water change.