Grooming a Springer Spaniel

Good morning,
I was wondering if anyone here has a suggestion for a good brush for a Springer Spaniel. His hair is very fine right now so I have been using something like this MiracleCorp Double Sided Brush by Miracle Coat - Grooming - Dog - PetSmart
and when his overall coat is longer I use this
Groomax® Slicker Brushes with Soft Grip Handle - New Puppy Center - Dog - PetSmart

The first brush doesn’t seem to do anything and the second one seems to hurt, even though I brush very gently. Any suggestions for a softer brush that will also de-shed?
Thank you!!

I have cockers. I honestly use a comb. Comb through the coat.. it removes dead hair, and then use a slicker on top after. Slicker brushes don't go deep enough to actually 'brush' more than the top most layers.

The comb works best - it takes a lot longer, but it is more thorough. And it makes it easier to be more gentle for fine coats. The slicker brush can scrape the skin on short (or fine) hair.