I had the same issue, with my 2015 34 PC. IF you have the shower wand, it does come apart. I took it off the hose and disassembled off the boat, fairly easy to do. Not sure which sink you're talking about, but as Afratki says, my galley sink aerator just screws off. The sink in the head is a little more tricky. There is an allen screw in the back of the handle that must be loosened to remove it, then you can use a wrench to take out the faucet cartridge, this allows you to backflush the aerator. Reverse the process to reassemble. Not real difficult, just a little messy.