Just an update to anyone interested, I seem to have defeated the black algae problem i've been experiencing. I completely flushed out the bilge cavity, scrubbed the black sludge on the bottom with a brush, added a couple of gallons of fresh water with a small amount of non-chlorine pool shock (a few tablespoons). Came back a few days later and all the black stuff was completely gone and the bilge was sparlking clean.