First, love the look of your barrel; the realism is really there!
Second, I'm doing something similar but as per Meyer's advice, I'm putting the barrel filter PRIOR to the bog so as to keep it from getting clogged as easily. The bog is the polisher and the drum is the prefilter, allowing me to have clearer pond water and an easier way to clean the filter proper (as opposed to bog backflushing as often). If you haven't finished yet, I'd put it ahead of your bog and run the stream from there, if you can.
I haven't camouflaged my drum yet but your paint job is inspiring!
Michael