I have never used a wet brine.
I make a simple dry brine and let it do the work of brining and flavoring the salmon.
Brown sugar (I like dark for the flavor it imparts)
Kosher salt (non - ionized)
Minced Garlic (fresh over the jar form)
Mix the sugar and salt in about a 4:1 ratio
Garlic 10ish cloves
Pinch of cayenne
Mix it all together in large non metal bowl
score the salmon on the meat side but not through the skin
cover the meat side of the fish with the brine and work it in the scores
place in non metallic storage container
cover and place it in fridge for 6-8 hours
The sugar and salt are hydroscopic and will draw out moisture from the fish and the brine will turn into a brown "syrup"
after brining time wash the filets gently getting all the globs of stuff off
then smoke as you have been.
The longer you leave this brine on the firmer the fish becomes and possibly a bit saltier too.
a vac packer is ideal for keeping smoked salmon