If you don't like sucking on the siphon, all you have to do is fill up the big tube with water, block the opposite end of pipe with your finger, then trying not to lose water, flip the big tube upside down. Release your finger slowly so the water slowly fills the smaller tube, then once again block it with your finger when the water has flowed to near the bottom of the smaller tube. Put the big tube back in the tank, fill with water (may need to tip it upside down in the tank) and then let to of your finger and it will flow. Sounds a but complex, but once you get the hang of it, it's really quick.