Hey there Jeremy, The mop and broom handles will work just fine. No more paint than are on them the algae will cover pretty quickly. I would not suggest using the metal pans though because they will be hard to get out of. Thw best thing that you can use is to go to the Dollar store or Wal-Mart and get the plastic 18 qt. dishpans for 2.00 each. Just keep popping these off and re-using them.
I read where one guy had access to a mill that made hardwood shovel handles and he got all their culls.