I have an in-line 3 inch chlorine tablet erosions dispenser for my pool.
Last spring I had a problem, in that the tablets were not dissolving. I
usually have to fill the dispenser once a week, but after two or three weeks
I just had to add 2 or 3 tablets. I purchased a different band of tablets
and system began working properly.

Now this year I am having the same problem with the brand that worked last
year and I have tired 2 other brands with the same results. I obtained a
floating dispenser and the tablets are not dissolving in it either. Even
putting them in the skimmer basket the tablets last several weeks.

I noticed some companies are advertising slow dissolving tablets. However,
with tablets in the floater, in the skimmer basket and in the dispenser my
chlorine level barely registers on my test kit. All my pool chemistry is
correct and I am now adding 2 gallons of liquid chlorine a week to keep the
algae under control.