I sat my pull up on saturday, got it filled by the evening time and the next morning I had the same thing, almost a rust color. It looked like someone splashed motor oil on the bottom of my pool and along the creases. It was very 'dusty' like. I stirred it up with the skim net, turned on my pump and ran it. Then turned around checked my filter the next morning and WOW! It looked like someone soaked my filter in tea. I back washed and with in a few hours it had happened again. This all just started with in 12 hours of the pool being filled. Don't think it's algae. I keep stirring it up and keep filtering a few hours a day. It's slowly going away. Seems it was a sediment in my water. It usually settles on the outside areas of the pool in the flow path.