trader_4 wrote, on Wed, 25 Jun 2014 08:06:58 -0700:

With 4 floaters, isn't the chlorine through the roof?

I understood everything you imply, as I am familiar with
the increasing ratio of CYA to target free chlorine level
as per this common table:

(Stabilizer) (Minimum FC) (Target FC) (Shock FC)
20 2 3 10
30 2 4 12
40 3 5 16
50 4 6 20
60 5 7 24
70 5 8 28
80 6 9 31
90 7 10 35
100 7 12 39
etc.

There is plenty of full sun here in summer in the NYC area
and with a 48,000 gallon pool, 1 floater loaded with
about 7 tabs keeps the chlorine at about 2 PPM.

I actually only have about 50 ppm CYA, even with adding the
powder, which means I need to target Free Chlorine at 6 ppm.

The question is why you need so much chlorine?

I realize it's not often stated at the pool store, but,
the chlorine number is wholly useless without the associated
CYA value.

For example, with your 2ppm of free chlorine, if you had
a 40 ppm CYA, you'd already be below the minimum, and far
below the target chlorine levels for your pool (based on
my read of the chart above).

I can only hope, for your sake, that your CYA is at or
below 30ppm, which, for a sunny area out here, would not
be enough stabilizer.

I've never seen a pool with more than one floating dispenser,
let alone four.

You haven't seen "my" pool!

Seriously though, I'm welcome and open to ideas, as I can't
seem to keep chlorine in this pool, even though the biological
load is nearly zero (nobody even swims in it lately).