I have plans for avoiding this problem in the future but first I need to
remove what's there now.



I don't have a suggestion for removing it, but to avoid it in the future,
install a tap kit (I forgot the exact name they use) . It takes a small
amount of the circulating water and dumps it out onto the lawn. This allows
the chemical concentraion in the system to reach an equalibrium level where
the concentration of chemicals does not go up indefintly. Without the tap
the water and all the chemicals goes in, the water evaporates and ALL the
chemicals remain in the cooler.

If you set up the tap so say 10% of the water is dumped and 90% evaporates,
then the concentration will go up to about 10x but no higher.

Mark