If you're having just a 1 ppm drop in chlorine overnight, that's a good thing. The CC is high but you're doing the right thing to get rid of it--just maintain your chlorine above 15 ppm and give it time to burn the CCs off. It will take time, but it will happen. Did you use foamy algaecides or other additives in the past that may be creating the foam? If you can skim some of that off with a net, it would probably help speed things up a bit. Also, what are you using to clean your cartridges? Is it possible that you're not completely washing all the detergent from the filters?

I think that running the pump without the filter in it is a waste of $$...if your pump has run enough after your bleach is added to sufficiently mix it (an hour or so), then I would just turn the pump off till the next day if you don't have a filter in place. The whole idea behind running the pump 24/7 is to capture as much of the dead algae in the filter as quickly as possible. One thing you might want to consider, though, is to buy a second filter cartridge--that way you could switch them out and always have a filter in place while you're cleaning the other one...just a thought?

Janet