Richard J Kinch wrote:
-snip-
Beware. My local pool store, one of the largest and well-known franchise
chains,

That's a point worth making. I probably have a dozen 'local stores'.
I trust 2 of them. I avoid the huge store like the plague.

I am one of the folks that recommended going to 'your local store'.
The one I go to now has saved me money & time by making complete tests
and recommending the right chemicals. I've been going there for 5
years & spend less than $200 a year maintaining a 24' round AG pool.
I buy tools there that are more expensive than the Walmart down the
street because I appreciate the time these guys have taken over the
years to solve 'mystery problems' with my water or equipment.
Someday I'll probably buy a pool or spa from them.

For 15 years prior to this pool place I used another similar outfit
who had some family sickness and had to close. I used 4 other shops
one time each in between the two. There are crooks & idiots out
there. There are also shops that can save you money & time-- and more
important, when it is 95 degrees- can get your pool usable again in a
hurry.

Find one before you need it.
Jim