I have a gutter system on my barn to catch rainwater in 55 gal. rain barrels. I use about 1/4 cup of laundry bleach to keep the algae from growing. As far as the pumpkin seed, they get soaked in salt water, baked & devoured.........by me. Last year after Halloween, Wal-mart sold the leftover "punkins" for 10 cents each. I got all my truck would haul. I got the seeds & horses & chickens got the rest.
