I am looking for an effective siphon and gravel vac that would work well in a 29-gallon. I currently have a small Python brand gravel vac. It works very well in my 10-gallon. In my 29-gallon, the suction is very weak and it takes forever to complete a cleaning. My brother gave me a length of thicker plastic tubing that he used to use in his tank. That one sucks the water out so quickly that I end up removing more water than I intend to each time I clean the tank. I'm hoping someone can suggest a good quality gravel vac that has nice suction, but not too fast for a 29-gallon. I have a sand substrate, so if there is something that works especially well with sand, that would be great too. Thanks!