The seaweed is much less for K than all the other goodness it brings, like trace elements and minerals. Not much of anything organic is really high in K, but then again, not much is really needed. I also use ProTekt (a liquid silica), for other reasons, but it is also very high in K. It's also used as a pH up and something similar should be very easy to locate down there.
Blood & Bone. Bone meal is pretty slow and should be added well in advance to the mix, like a month or longer in advance. I add it in the fall to my wife's flower beds for the following spring bloom. Blood meal is just the opposite, becoming available in a couple of weeks after adding it, Same flower bed, blood meal gets added 2-3 weeks before new growth is expected to 'pop'. If you can get them seperate rather than combined it would be better, but not essential. Just make sure the bone meal has some time to break down and become available.
Wet