Directions and a video for use of the ND Filter Cap.
1). Collect 2L of water in a clean 2L soda bottle.
2). Screw the filter cap on. Flip the bottle upside-down.
3). Use a thumbtack or safety pin to poke a hole in the bottom of the bottle. This will break the vacuum and let water flow out in a steady stream.
4). It will take about 5 min to drain out. Don't squeeze the bottle or rest the cap on the bottom of the sink.
5). Unscrew the filter cap and put it back into the zip-top baggie.