How weird, I posted to this thread this morning and it isn't here. If anyone else notices anything like that, let me know!
What I'd said was -- this is almost certainly Zack losing his puppy coat. They tend to 'blow' it, as the terminology goes, when they are getting to around a year old but sometimes younger and sometimes much older.
So a lot of hair will come out then probably not as much again at one time. Cavaliers don't have an undercoat so a tool designed to help thin undercoats probably won't do much. If you twine a rubber band through the teeth of a comb that can help take out loose hair. Or the mitts work, or just brushing well each day. Different brushes are better than others. A soft brush won;t take pout much. I like my boar bristle brush for taking out dead hair but pin slicker brushes are good (mine hate them on their skin though so I can't use them for overall brushing). I use pin brushes with rubberised tips on the pins and that works well too.
Different dogs shed more hair than others generally. Neither of mine are big shedders -- that job goes to the cats in my house!! However I grew up with a Great Pyrenees and a cavalier is never, ever going to come close in the shedding stakes to a pyr; now those are REAL tumbleweeds of hair!! Years after she passed on, my mom would find birds' nests lined with her soft hair which was still into everything out in the garden.
Of course your best tool is going to be
Judy I'd also be very cautious of using a blade tool. You aren't taking out dead hair, you are actually cutting his hair and thinning his coat with one of those. That may not be what you want to do and it is also easy to overdo it and find you've taken out huge chunks of coat that will take a long time to regrow. A thinning tool is really useful for adult dogs with very heavy coats that people might want to thin out. The Mars Coat King has a thinning tool that lots of cavalier breeders use and recommend them.
People recommend the 16 or 20 for cavaliers. Note they should only be used once a week or two weeks.